WASHINGTON, United States (AFP) — International efforts to mediate between the US and Iran were in the balance on Sunday, after President Donald Trump canceled his envoys' planned trip to Pakistan for talks.

Trump said there was no point "sitting around talking about nothing" and dismissed Tehran's negotiating position, but added that Iran had revised its proposal within minutes of his decision.

"They gave us a paper that should have been better and — interestingly — immediately, when I canceled it, within 10 minutes, we got a new paper that was much better," he told reporters, without elaborating.

The White House had said Trump's son-in-law Jared Kushner and special envoy Steve Witkoff were to set off for Pakistan on Saturday for talks with Iran aimed at moving "toward a deal," but Trump later told Fox News he had scrapped the trip.

"We have all the cards. They can call us anytime they want, but you're not going to be making any more 18-hour flights to sit around talking about nothing," the president said he had told his team.

'Very fruitful'

Asked separately whether the cancelation meant a return to hostilities, Trump said: "No, it doesn't mean that. We haven't thought about it yet."

Later, after a gunman was arrested at the White House Correspondents' Association dinner in Washington, Trump said he did not think the incident was related to Iran but that it would not deter him "from winning the war."

Shortly beforehand, Iranian Foreign Minister Abbas Araghchi wrapped up a visit to Islamabad after meeting Pakistan's military chief Asim Munir, a key mediator, Prime Minister Shehbaz Sharif and Foreign Minister Ishaq Dar.

Iran said Araghchi had left for Muscat and would return to Pakistan on Sunday after meetings in Oman, before traveling on to Russia for talks on ending the war launched by the United States and Israel on 28 February.

Araghchi described his Pakistan trip as "very fruitful" but signaled skepticism over Washington's intentions.

"Have yet to see if the US is truly serious about diplomacy," he said.

Even before Trump's move, prospects for talks were uncertain, with Iranian state television saying Araghchi had no plans to meet US officials and that Islamabad would act as a conduit.

Sharif said he had spoken to Iranian President Masoud Pezeshkian and reiterated Islamabad's commitment to facilitating "durable peace."

Iranian state TV said Pezeshkian told Sharif the Islamic republic would not be coerced by Washington's "hostile actions."

Hormuz blockade deepens

Pressure to end the war has intensified as the Strait of Hormuz — a vital oil and gas route — remains closed.

But Iran's powerful Revolutionary Guards said they had no intention of lifting their blockade, which has roiled energy markets.

"Controlling the Strait of Hormuz and maintaining the shadow of its deterrent effects over America and the White House's supporters in the region is the definitive strategy of Islamic Iran," the Guards said on their official Telegram channel.

The US has imposed a blockade of Iranian ports in retaliation.

In a statement carried by state media, Iran's military warned that continued US "blockading, banditry and piracy" would draw a response.