Washington DC - President Donald Trump said he's not ready to seek a deal to end his war on Iran, threatening instead to launch more attacks "just for fun."

In an interview with NBC News, Trump claimed Iran was keen to come to the table but that he would instead fight on for better terms.

He then hinted that the US might bomb targets on Tehran's oil hub Kharg Island once again, "just for fun."

Trump also warned that US forces would step up strikes on the Iranian coast north of the Strait of Hormuz to clear up oil shipping routes.

Donald Trump Trump issues desperate call to "send ships" as Iran holds firm on Strait of Hormuz

Iran's new supreme leader, Ayatollah Mojtaba Khamenei, vowed to keep the vital waterway closed, but Trump – who had earlier called for countries to "send ships" and challenge the blockade – cast doubt on his authority.

"I don't know if he's even alive. So far, nobody has been able to show him," he said.

Iran insisted on Saturday that "there is no problem with the new supreme leader", even though he has yet to appear in public. Khamenei was reportedly injured in the Israeli strikes that killed his father and most of his immediate family.

In an interview with MS NOW's Ayman Mohyeldin, Iranian foreign minister Abbas Araghchi also clarified that the Strait of Hormuz was only closed to US and Israeli ships, as well as those of their allies contributing to the unprovoked war.

The Israeli military, meanwhile, announced a wave of strikes against targets in Western Iran, after Iran's Revolutionary Guards branded Prime Minister Benjamin Netanyahu a criminal and vowed that they would pursue and kill him.