Top Iranian and US officials have held talks at the UN in New York on a day when the US leader said he could “annihilate” the Islamic Republic if the conflict went unresolved.

No breakthrough has been reported from the meeting mediated by Qatar and involving Iran’s foreign minister and US President Donald Trump’s envoy Steve Witkoff – the first since a June ceasefire unravelled.

Witkoff said a round of discussions had been completed “that we hope will prove constructive and promising”. Iran repeated its demand for the US to end its “acts of aggression”.

The US and Israel launched air strikes on Iran on 28 February. Iran responded by attacking Israel and US bases in the Gulf and Arab Gulf allies of the US – as well as blocking the Strait of Hormuz.

Some 20% of the world’s oil and liquefied natural gas used to pass through the strait before the war and its closure has caused wild fluctuations of prices.

It has also increased pressure on Trump to find a way of ending the conflict – particularly as the US heads to Congressional elections in November.

In his address at the annual meeting of the UN General Assembly in New York on Tuesday, Trump began by touting his accomplishments on the economy, immigration, the border and tackling violent crime – remarks that sounded more pitched to voters the US midterms than the diplomats in the hall.

He spent much of his address justifying the war with Iran – a huge contrast with remarks earlier by UN Secretary General António Guterres, who warned global divisions were deepening and underscored the “interdependence” of the world’s peoples.

The US president argued that the conflict had prevented Tehran from obtaining a nuclear weapon and demonstrated the value of what he described as peace through strength – ultimatums rather than deal-making or compromise.

“Will a deal be made with Iran that lets them rebuild and create a far greater country than it ever was before?” he said.

“Or do I annihilate the Islamic Republic and do it quickly, never giving them a chance to kill and destroy people and countries again? Do I drive them into hell?”

Trump said he believed an Iran deal, which has so far eluded him, would come right after November’s elections.

The remarks were indicative of his foreign-policy strategy of coercive diplomacy – threatening overwhelming force while keeping negotiations open.

Trump later told reporters that American officials had had a “very productive” three-hour meeting with the Iranian delegation on the sidelines of the general assembly.

Iran state TV confirmed that Foreign Minister Abbas Araghchi had met Witkoff.

Iranian foreign ministry spokesman Esmail Baghaei, quoted by state broadcaster IRNA, later said negotiations took part through a Qatari mediator who communicated Tehran’s conditions, including an end to the war on all fronts and to US “acts of aggression”.

The BBC asked Witkoff how the meetings had gone as he was leaving the UN building and he responded with a thumbs up. Witkoff later confirmed on X that the talks had been held “through the mediators, who shuttled between the two sides throughout the day”.

“They successfully completed a round of discussions that we hope will prove constructive and promising,” Witkoff said. “The mediators will continue their work.”

Since the ceasefire collapsed, both sides have intermittently exchanged fire.

Iran has attacked vessels it says have attempted to cross the Strait of Hormuz without authorisation.

The US has attacked Iranian sites in the strait – as well as Iranian tankers off the country’s coast.

The US has also maintained a blockade of Iranian ports, causing a huge disruption to the Iranian economy.

In an effort to force Tehran to agree a deal to end the conflict, President Trump has also threatened sanctions against any country that continues trading with Iran. But so far, there has been no indication of a change of course in Iran, which insists the US and Israel end their war, including against the Iran-backed Shia group Hezbollah in Lebanon which Israel has been attacking.

Yemen’s Houthis – also allied to Iran – have recently intesified attacks aimed at disrupting oil shipping from Saudi Arabia, promting an escalation of the conflict with the kingdom.