New protests have erupted in Iran as a wave of anti-government rallies that began last week shows no sign of losing its momentum.

Iranian state media has said that 14 people and one policeman have been killed after five days of demonstrations in different cities across the country. Some 400 protesters have reportedly been arrested.

The reports, which have not been independently verified, also said security forces repelled "armed protesters" who tried to take over police stations and military bases.

In the capital, Tehran, police on Monday evening used tear gas and water cannon to disperse a small protest near Engheleb Square.

"This is better than staying silent," Milad, a young protester told Al Jazeera, his eyes red from tear gas.

Nearby, Aslan, a 52-year-old man in the area who was not demonstrating, said protesters "need a chance to show they are not happy".

"The government should let them protest," he told Al Jazeera.

Also on Monday, a report by Iran's semi-official Mehr news agency said a police officer was killed, and three others were wounded in the central city of Najafabad after being shot by an assailant using a hunting rifle. It was not clear when the incident took place.

'Shake people in power'

Sparked by anger over the state of the economy and the high cost of living, the rallies began on December 28 in the second-largest city of Mashhad.

Despite threats by the Republican Guards to put down the demonstrations, protesters have continued taking to the streets in other parts of Iran, in what has been described as the biggest show of dissent in the country since huge rallies took place in 2009.

"We cannot predict a time when the protests will come to an end," said Sadegh Zibakalam, an author and academic.

"But the protests will shake the people in power who must give priority to the people's demands and needs."

On Sunday, President Hassan Rouhani said Iranians have the right to protest but not violently.

"People are free to express their criticism and to protest," he said in televised remarks, his first since the rallies began.

"However, we need to pay attention to the manner of that criticism and protest. It should be in such a way that it will lead to the improvement of the people and state," he added.

"People have the right to protest, but those demonstrations should not make the public feel concerned about their lives and security."

In May 2017, Rouhani, who belongs to the reformist bloc of Iran's political spectrum, decisively won re-election after garnering 57 percent of the vote in the country's presidential election.

That poll was the first since Rouhani negotiated a historic deal with world powers in 2015 to curb Iran's nuclear programme in exchange for sanctions relief.

Many in Iran hoped that the deal, by lifting many international sanctions, would ease the country's financial struggles.

Yet, the benefits do not seem to have trickled down, leading many to protest against rising unemployment, income inequality and the high cost of living.

Ali Vaez, the Iran project director at the International Crisis Group who worked with all sides during the negotiations for the nuclear deal, said the fact that the nuclear deal did not quite deliver the results people expected played a key part in what is happening currently in Iran.

"The government inflated public expectations a lot," Vaez told Al Jazeera, noting that factors such as falling oil prices and doubts over the US' commitment to the deal were also adversely affecting the Iranian economy.

"The reality is, however, that President Rouhani failed to pave the ground for the potential the nuclear deal created, and that has led to a lot of frustration in Iran," he said. "President Rouhani over-promised and under-delivered."

Mohammad Ali Shabani, an Iranian political analyst and scholar, agreed.

"The issue is elevated expectations, that's where the danger comes in," he told Al Jazeera.

"People have been expecting better lives, partly as a result of Rouhani's promises in connection with the nuclear deal," explained Shabani.

"It's not a matter of absolute poverty driving people into the streets. It's mostly about people thinking that 'We need more than this, we were actually promised more than what's happening, and we don't have the jobs that we were anticipating'."

'Varied demands, varied responses'

Protesters have railed at the ruling religious elite, whom they blame for economic hardships and alleged corruption.

Anger, however, has not been limited to financial grievances; it has also shifted to Iran's foreign policy.

Some protesters have been critical of Iran's regional policies in countries such as Syria and Lebanon, while others have chanted slogans against Rouhani as well as Supreme Leader Ayatollah Ali Khamenei.

Unlike the mass protests of 2009 that followed the disputed re-election of then-President Mahmoud Ahmadinejad, the recent demonstrations appear to be more spontaneous, decentralised and without clear figureheads.

"We don't know who precisely is behind the protests - they do not have the same kind of leadership as in 2009," said Shabani, underlining the protesters' different complaints.

"You have varied demands, and also you have varied responses from Iranian leaders," he added.

"Initially they were opposed to high prices, some now say 'Death to Khamenei' and 'Death to Rouhani', so they are targeting different political figures, different power centres and they have different demands.

"What the Iranian leaders have been saying is that 'there are two types of protesters: those with genuine economic grievances who have the right to protest, and those who are after a different thing which we do not accept', referring to people who call for Khamenei's death for instance, so that dynamic is quite interesting."

Netanyahu echoes Trump

US President Donald Trump has been quick to respond to the protests, saying Washington is "watching very closely for human rights violations".

"The people are finally getting wise as to how their money and wealth is being stolen and squandered on terrorism," he said on Twitter on December 31.

Rouhani has hit back at Trump on Sunday, accusing him of having "forgotten that he has called the Iranian people 'terrorists' a few months ago".

On Monday, the Iranian president was quoted by state media as apparently accusing Iran's enemies - the US and Israel - of being behind the protests.

"Our success in the political arena against the United States and the Zionist regime was unbearable to (Iran's enemies). Iran's success in the region was unbearable to them. Don't you expect that they would seek revenge? Don't you think they would provoke some people?" Rouhani said in a meeting with politicians.

In response, Israeli Prime Minister Benjamin Netanyahu said Rouhani's suggestion that Israel was involved was "not only false - it's laughable".

Netanyahu added that more Western countries should condemn Tehran for trying to put down the protests.

"Sadly many European governments watch in silence as young heroic Iranians are beaten in the streets. That's just not right. And I, for one, will not stay silent," he said.

With additional reporting by Saeed Jalili