Iran has threatened to pursue and destroy any aggressor, and says war may be unavoidable in the wake of drone attacks on Saudi Arabian oilfields and a US troop build-up in the Gulf.

A day after the head of Iran’s elite Republican Guards said on state TV that “limited aggression will not remain limited,” the Iranian foreign minister told American network CBS that he was not confident that war could be avoided, while again denying Iranian involvement in the attacks on Saudi Arabia.

In an interview with Face the Nation due to be aired Sunday morning, US time, foreign minister Javad Zarif said: “I’m not confident that we can avoid a war. I’m confident we will not start one, but I’m confident that whoever starts one will not be the one who finishes it.”

Asked by host Margaret Brennan what that meant, Zarif replied: “That means there won’t be a limited war.”

The US and Saudi Arabia have repeatedly accused Iran of being behind the 14 September attacks on Saudi oilfields, which were claimed by Yemen’s Houthi movement, a group aligned with Iran and currently fighting a Saudi-led alliance in Yemen’s civil war.

Zarif, who is in New York for the United Nations general assembly, said he was confident Iran played no role in the attack, and described the US decision to send troops to bolster Saudi air defences as unhelpful posturing.

A satellite image of the aftermath of the 14 September attack on Saudi Aramco’s Abqaiq oil processing facility. Photograph: AP

He said any independent inquiry would clear his country. “These attacks did not take place from Iran for the supreme leader to approve them,” Zarif said. “Had they taken place from Iran then he would have had to approve them. But it didn’t take place from Iran.”

The interview came after the head of the Republican Guards, Maj Gen Hossein Salami, said on Iranian TV on Saturday: “Be careful, a limited aggression will not remain limited. We will pursue any aggressor. We are after punishment and we will continue until the full destruction of any aggressor.”

Donald Trump on Friday approved sending American troops to bolster Saudi Arabia’s air and missile defences. Trump’s move drew fire in Washington on Saturday from House speaker Nancy Pelosi, who called it his “latest outrageous attempt” to circumvent Congress.

“These unacceptable actions are cause for alarm,” Pelosi said in a statement accusing Trump of turning “a blind eye” to Saudi violence against innocent Yemenis, human rights abuses and the murder of journalist Jamal Khashoggi.

“The United States cannot enable more brutality and bloodshed,” she added. “Congress will do our job to uphold the constitution, defend our national security and protect the American people.”

Revolutionary Guards commander Hossein Salami speaks at Tehran’s Islamic Revolution and Holy Defence museum. Photograph: Atta Kenare/AFP/Getty Images

Meanwhile, the head of the Revolutionary Guards’ aerospace branch, Amirali Hajizadeh, said any attacks on Iran would receive “a crushing response“, the official news agency IRNA reported.

Hajizadeh was speaking at a public exposition called Hunting Vultures, where what Iran said were remains of downed drones were displayed, along with the Iranian air defence system that shot down a US military drone in June.

The exposition is part of annual events commemorating the start of the 1980-88 war with Iraq, which also includes air and naval displays in the Gulf and military parades on Sunday.

Earlier, foreign minister Zarif had denounced renewed US sanctions against its central bank following the Saudi attacks as an attempt to deny ordinary Iranians access to food and medicine, and said the move was a sign of US desperation.

The US on Friday imposed more sanctions, targeting the Central Bank of Iran, the National Development Fund of Iran – the country’s sovereign wealth fund – and an Iranian company that US officials say is used to conceal financial transfers for Iranian military purchases.

“This is a sign of US desperation ... When they repeatedly sanction the same institution, this means their attempt at bringing the Iranian nation to its knees under ‘maximum pressure’ has failed,” Zarif told state television.

“But this is dangerous and unacceptable as an attempt at blocking ... the Iranian people’s access to food and medicine.”

Separately, Foreign Ministry spokesman Abbas Mousavi rejected what he called “unreal and repetitious accusations by certain Saudi officials” about the attacks, state media said.

Iran’s foreign minister, Javad Zarif. Photograph: Evgenia Novozhenina/Reuters

A senior Saudi official said earlier that Riyadh would wait for the results of a probe before responding to the attacks on its oil facilities, for which it believes Iran is responsible.

Zarif said he would on Wednesday meet foreign ministers of the remaining signatories to the 2015 nuclear accord, which was agreed with Britain, France, Germany, China and Russia as well as the United States.

“As we have said before, the United States can only attend if it returns to the (nuclear accord) ... and ends its economic war against Iran,” Zarif said.

The United States withdrew from the accord last year and re-imposed unilateral sanctions on Iran.

After reports on social media of a cyber-attack on some petrochemical and other companies in Iran, a state body in charge of cyber security denied there had been a “successful” attack.