United States President Donald Trump said on Tuesday the US is not pushing to topple Iran's leadership but is determined to stop it acquiring nuclear weapons.

“We are not looking for regime change. We are not looking for that at all,” Trump said during a cabinet meeting.

“They can't have a nuclear weapon.”

The US quit an international deal aimed at curbing Iran's nuclear programme last year, hitting Tehran with crippling sanctions.

Iran said last week that it had enriched uranium past the 3.67 per cent limit set by the 2015 nuclear deal, and has also surpassed the 300-kilogram cap on enriched uranium reserves.

Tensions have soared since Trump pulled out of the deal, with the US calling off air strikes against Iran at the last minute after Tehran downed an American drone, and Washington blaming the Islamic republic for a series of attacks on tanker ships.

Iranian Foreign Minister Mohammad Javad Zarif warned on Monday that the US is “playing with fire.”

According to leaked diplomatic cables published at the weekend, Britain's ambassador to Washington believed Trump pulled out of the nuclear deal because it was associated with his predecessor Barack Obama.

“The administration is set upon an act of diplomatic vandalism, seemingly for ideological and personality reasons — it was Obama's deal,” wrote the envoy, Kim Darroch, who resigned amid a storm triggered by the release of the sensitive documents.