The Egyptian president, Mohamed Morsi, has vowed there will be no second revolution in Egypt, as thousands planned to gather outside his presidential palace calling for his removal after a year in power.

In an exclusive interview with the Guardian, Morsi rejected opposition calls for early presidential elections and said he would not tolerate any deviation from constitutional order. He said his early resignation would undermine the legitimacy of his successors, creating a recipe for unending chaos.

"If we changed someone in office who [was elected] according to constitutional legitimacy – well, there will be people opposing the new president too, and a week or a month later they will ask him to step down," Morsi said.

"There is no room for any talk against this constitutional legitimacy. There can be demonstrations and people expressing their opinions. But what's critical in all this is the adoption and application of the constitution. This is the critical point."

At least seven people have been killed and over 600 injured in clashes between Morsi's Islamist allies and their secular opposition over the past few days.

With tensions set to rise on Sunday, Morsi's defiant stance sets the stage for a trial of strength that will be played out on the streets of Cairo in front of his official residence. Once gathered, the opposition have vowed not to leave it until he resigns.

The man at the centre of a national storm seems uncannily certain of himself and his staying power. Asked whether he was confident that the army would never have to step in to control a country that had become ungovernable, Morsi replied: "Very."

But Morsi's assured demeanour contrasted with the tense atmosphere that surrounded him on Saturday afternoon. Morsi held back-to-back meetings with top-level state officials, including the prime minister, Hisham Qandil, the interior minister, Mohamed Ibrahim, and several senior officers, including the head of the armed forces, General Abdel Fattah Sisi – whose ambiguous comments in recent days have led to widespread hopes in opposition ranks of military intervention.

Morsi had decamped from Itahadiya palace, the traditional seat of the president, which is now surrounded by makeshift concrete walls in anticipation of Sunday's protests. In its place, he held court on Saturday at the Quba Palace, the birthplace of Farouq – the last king of Egypt.

Morsi claimed Egyptian private media channels had exaggerated the strength of his opponents, and blamed this week's violence on officials loyal to the former president Hosni Mubarak.

He said the media had taken "small situations of violence and then magnified them as if the whole country is living in violence". He dismissed the organic nature of the opposition to his rule, and maintained that the fighting had been co-ordinated by "the deep state and the remnants of the old regime" who had paid off hired thugs to attack his supporters in the Muslim Brotherhood.

"They have money, and they got this money from corruption. They used this corrupt money to pull back the regime, and pull back the old regime into power. They pay this corrupt money to thugs, and then violence takes place."

The president refused to name which countries were meddling in Egypt's affairs, but maintained that it was happening. Asked whether he was referring to Saudi Arabia and the United Arab Emirates, Morsi replied: "No, I am talking in general terms. Any revolution has its enemies and there are some people who are trying to obstruct the path of the Egyptian people towards democracy. I am not saying it's acceptable, but we observe it everywhere."

Morsi admitted for the first time in the English-language media that he regretted making a constitutional declaration that gave him wide powers – a move that the opposition saw as dictatorial, and which he soon rescinded. This was the pivotal moment of his first year, sowing the seeds for widespread dissent against his administration.

"It contributed to some kind of misconception in society," Morsi said, distancing himself from one of the most divisive clauses in the new Islamist-slanted constitution, which allows for greater religious input into Egyptian legislation. "It's not me who changed this article. I didn't interfere in this constitutional committee's work. Absolutely not."

He said that once MPs were finally elected to Egypt's currently empty lower house of parliament, he would personally submit constitutional amendments for debate in the house's first session.

But Morsi's contrition only went so far. Amid opposition claims that the failure to achieve consensus had led to Egypt's current polarisation, Morsi blamed the refusal of secular politicians to participate in the political process for the impasse.

He denied that his government was unduly loaded with Islamists. He went on to list numerous offers he claimed he had made to bring non-Islamists on board, while defending the right of a popularly elected president to promote his allies. "This is the concept of real democracy," he said.

Morsi denied that he had ever offered the leading secular politician Mohamed ElBaradei a job, but named Mounir Fakhry and Gouda Abdel Khalif as two opposition ministers who left his cabinet against his wishes. "That's the situation," Morsi claimed. "We offer people [jobs] and they refuse."

Even now, Morsi said, the offer for dialogue with opposition members remained open – though the opposition say such meetings are a waste of time because Morsi only pays lip-service to their point of view.

Morsi has been criticised for betraying a key goal of the 2011 uprising that toppled Mubarak: security sector reform. Since rising to power, Morsi has avoided criticising the police, even in the face of allegations of extreme malpractice. In January after more than 40 people died in gun battles with security officials in Port Said, Morsi praised the police and gave them more powers.

Asked why he had repeatedly refused to criticise specific instances of police malpractice, the president claimed that his praise was meant in a more general sense. "When I say I am supporting the police or the army, I am talking about the army in general and the police in general. In general, those institutions are good institutions. Accordingly if there are certain violations, or crimes, or abuses by certain individuals – well, the law takes its course."

But Morsi has even been accused of kicking into the long grass allegations of security force brutality under previous regimes. After his election he commissioned a fact-finding report on police and military wrongdoing during and after the 2011 uprising. But he has never published its findings, and when its damning contents were leaked to the Guardian in April, Morsi chose to praise the army and police, and promoted three generals.

"I'm supporting the institution," he again claimed this weekend. "I'm not supporting the individuals. And of course, the number of people who committed the violations are very small in comparison to the institutions."

Morsi appeared to be treading a fine line between blaming stubborn state institutions for the failures of his administration in one moment, while embracing them in the next – perhaps to avoid making the situation worse.

Throughout the one-hour interview, Morsi hinted that the intransigence of Mubarak-era state officials was holding up reform of state institutions such as the interior ministry, who control the police. He noted the stubbornness of "a deep state and its impact on running the country, and the desire of some people who come from the previous regime to [create] corruption", calling the extent of state corruption one of the most unpleasant discoveries of his first year.

While peppering his remarks with frustration at Egypt's "deep state", Morsi stressed his faith in the military high command – and in particular in Sisi. He admitted that he had no prior warning of Sisi's comments last Sunday, in which the general appeared to give civilian politicians a week to resolve their differences.

"We constantly talk together over time," Morsi said, but "we can't restrict every single word announced by officials in this country". Glancing at his spokesmen for the first time in the interview, Morsi also claimed that the army had been burned by their previous involvement in power, and said: "They're busy now with the affairs of the army itself".

Morsi emphasised his democratic legitimacy. But while acknowledging that he was elected freely and fairly, many of his opponents argue that he does not uphold the wider democratic values on which a successful democracy relies.

Among many other complaints, critics condemn his appointment of Talaat Abdallah as attorney general, claiming that Abdallah pursues political cases against activists and media personalities critical of the president – such as Alaa Abdel Fattah, who rose to prominence during the 2011 uprising, and Bassem Youssef, Egypt's leading satirist.

But Morsi refused to accept this argument, arguing that Abdallah operated independently. "The cases you're talking about, they were filed by citizens or by lawyers, and the prosecution dealt with [them]. And the prosecution and the judicial system are fully independent," he argued. "If someone wants to say that I interfered in the work of the public prosecutor, he has to provide evidence of that, and an example of that."

As his opponents bank on this year being his last, Morsi confidently predicted that he would serve a full term. "It has been a difficult, very difficult year. And I think the coming years will also be difficult. But I hope that I will all the time be doing my best to fulfil the needs of the Egyptian people and society."

The problem remains that Egypt is bitterly divided on whether he should be allowed to do so.