Trump Declares Iran Ceasefire Over Amidst Escalating Gulf Tensions

US President Donald Trump says he believes his country's ceasefire with Iran is over, responding to a question about the state of the truce following fresh attacks across the Gulf.

Whether it means a return to all-out war remains to be seen, given Mr Trump said he would continue speaking with his negotiators Steve Witkoff and Jared Kushner about the next steps.

But he labelled the Iranians as "liars", "scum" and "sick people".

"They're cuckoo. As far as I'm concerned, it's over," he said at a NATO summit in Türkiye.

It comes after the US military launched fresh strikes against Iranian ships in the Persian Gulf, in response to attacks on tankers in the Strait of Hormuz.

The US also revoked a licence allowing Iran to sell oil, a key part of the memorandum of understanding signed by Mr Trump and Iran's President Masoud Pezeshkian just three weeks ago.

In response, Iran launched missiles and drones across the Gulf, targeting countries such as Bahrain and Kuwait.

Kuwait's state news agency said two ballistic missiles and 13 drones were fired at the country on Wednesday morning, local time, but there was no damage or casualties recorded other than some downed powerlines.

"They're liars, they're cheats, they're sick people," Mr Trump said, sitting alongside the secretary-general of NATO, Mark Rutte, in the Turkish capital, Ankara.

"I'll let our wonderful negotiators keep talking, but I don't like it," he said.

The week-long funeral procession for former Iranian Supreme Leader Ali Khamenei has been underway for a number of days, leading to a pause in the technical talks between Iran and the US on a lasting peace deal.

"We said, 'Go and do your funeral stuff,' and instead of that they started shooting rockets at ships yesterday," Mr Trump said.

"And so we hit them very hard last night, very hard — I would say 20 to 1, 20 times tougher.

"And I told them, 'Every time you hit, we hit.'"

On Tuesday, before Mr Trump's comments, Iran's Foreign Minister Abbas Araghchi issued a warning to the United States to tone down its threatening rhetoric.

Oman, the country on the other side of the Strait of Hormuz from Iran, condemned the latest strikes across the Gulf.

"The Sultanate of Oman affirms that the escalation of military tensions in the region poses a threat to its security, to navigational safety, to the smooth flow of international trade, and to energy supplies, renewing its total rejection of any actions that would undermine the security of states or expose civilian and commercial ships to danger," its foreign ministry said on social media.

"The Sultanate of Oman calls on all parties to exercise restraint, halt the escalation, prioritize the language of dialogue and diplomatic solutions, and commit to the full implementation of the signed understandings in support of efforts to consolidate security and peace."

The European Union also called for calm.

"The exchanges of fire between the US and Iran further complicate already fraught talks to end the war," the EU's top diplomat, Kaja Kallas, said.

"Iran's attacks on Bahrain and Kuwait are unacceptable."

Global oil prices soar after Trump's latest comments

Mr Trump's statements on the Iran war have sent shock waves through global financial markets.

The price of global oil benchmark, Brent crude, has soared 6 per cent to near $US79 ($114) a barrel.

Gold has slumped 1 per cent.

European stock markets fell heavily at the open of trade with Germany's DAX slumping over 2 per cent.

Wall Street futures markets, which point to the opening of share trading in the US, are also down sharply.

The Australian dollar has dropped to about 69 US cents.