In a social media post Sunday, Trump also accused Iran of violating the countries' two-week ceasefire with attacks Saturday in the Strait of Hormuz.

Trump said he was offering Iran "a reasonable deal" and if Tehran refuses, "the United States is going to knock out every single Power Plant, and every single Bridge, in Iran. NO MORE MR. NICE GUY!"

In his fresh threat, made on his Truth Social platform, Trump said of Iran's bridges and power plants: "They'll come down fast, they'll come down easy and, if they dont take the DEAL, it will be my Honor to do what has to be done, which should have been done to Iran, by other Presidents, for the last 47 years."

The Strait of Hormuz remained closed on Sunday amidst the stand-off. Iran on Saturday declared it shut again to shipping after it had on Friday announced it was reopening the strategic waterway.

The US-Iran ceasefire is scheduled to end on Wednesday.

As mediation efforts continued following high-level talks in Pakistan on April 11-12 that failed to reach a deal, Iran said it would not reopen the strait until the United States ended its blockade of Iranian ports.

Trump wrote Sunday, "Iran decided to fire bullets yesterday in the Strait of Hormuz - A Total Violation of our Ceasefire Agreement!"

Three incidents Saturday demonstrated the dangers of any attempted crossing of the strait.

A UK maritime security agency said Iran's Revolutionary Guards fired at one tanker, while security intelligence firm Vanguard Tech reported the force had threatened to "destroy" an empty cruise ship that was fleeing the Gulf.

In the third incident, the UK agency said it received a report of a vessel "being hit by an unknown projectile, which caused damage" to shipping containers but no fire.