Negotiations between the two countries have been deadlocked since a ceasefire came into effect on April 8, with only one round of direct peace talks held so far.

Iran's Tasnim and Fars news agencies reported that Tehran had submitted a 14-point proposal to mediator Pakistan, but Trump was quick to cast doubt on it.

"I will soon be reviewing the plan that Iran has just sent to us, but can't imagine that it would be acceptable in that they have not yet paid a big enough price for what they have done to Humanity, and the World, over the last 47 years," Trump said on his Truth Social platform.

US news website Axios reported, citing two sources briefed on the proposal, that it set "a one-month deadline for negotiations on a deal to reopen the Strait of Hormuz, end the US naval blockade and permanently end the war in Iran and in Lebanon".

In a statement on Sunday, the Revolutionary Guards sought to put the onus back on Trump, saying he must choose between "an impossible operation or a bad deal with the Islamic Republic of Iran".

"The room for US decision-making has narrowed," they said.

The day before, Deputy Foreign Minister Kazem Gharibabadi told diplomats in Tehran that "the ball is in the United States' court to choose the path of diplomacy or the continuation of a confrontational approach".

Iran, he said, was "prepared for both paths".

- 'If they misbehave' -

In a brief interview with reporters in West Palm Beach, Florida, on Saturday the US president declined to specify what could trigger new American military action.

"If they misbehave, if they do something bad, but right now, we'll see," he said. "But it's a possibility that could happen, certainly."

In yet more bellicose rhetoric, Mohsen Rezaei, a military adviser to Iran's Supreme Leader Mojtaba Khamenei, said Iranian forces would sink US ships.

"The US is the only pirate in the world that possesses aircraft carriers. Our ability to confront pirates is no less than our ability to sink warships. Prepare to face a graveyard of your carriers and forces," he posted on X.

There is no evidence that Iran has sunk any US military vessels during the war.

Axios reported earlier in the week that Trump's envoy Steve Witkoff had asked for Tehran's nuclear programme to be put back on the negotiating table.

But Iran's mission to the UN pointed to the massive US nuclear arsenal, accusing Washington on Saturday of "hypocritical behaviour" towards Iran's own atomic ambitions.

- 'Trying to endure' -

Iran has maintained a stranglehold on the Strait of Hormuz since the war began, choking off major flows of oil, gas and fertiliser to the world economy, while the United States has imposed a counter-blockade on Iranian ports.

Oil prices are about 50 percent above pre-war levels.

The deputy speaker of Iran's parliament, Ali Nikzad, said that under draft legislation being considered for managing the strait, 30 percent of tolls collected would go towards military infrastructure, with the rest earmarked for "economic development".

"Managing the Strait of Hormuz is more important than acquiring nuclear weapons," he said.

In Iran, the war's economic toll is deepening, with oil exports curtailed and inflation surging past 50 percent.

"Everyone is trying to endure it, but... they are falling apart," 40-year-old Amir, a Tehran resident, told an AFP reporter based outside the country.

"We still have not seen much of the economic effects because everyone had a bit of savings. They had some gold and dollars for a rainy day. When they run out, things will change."

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