Donald Trump says he has cancelled strikes against Iran provided a deal was struck "rapidly" with the country.

In a post on Truth Social, the US president claimed he was asked by Iran and other countries in the Middle East to "hold off" on any attack as the "perimeters" of a deal had been agreed, which he said would include reopening the Strait of Hormuz and ending Iran's nuclear threat.

His comments came after US media reported that Washington may have been planning new, intense strikes on Iran over the weekend.

Earlier on Saturday, Tehran had accused the US of escalating tensions, saying any regional state co-operating with Washington would be "engulfed by the flames of war".

Meanwhile the US government urged Americans across the Middle East to be alert and ready to leave "should there be escalation" in the region.

"Americans currently in the Middle East should exercise caution and heightened vigilance and should be prepared for flight cancellations, periodic airspace closures, and potential travel disruptions," the security alert said on Saturday.

Multiple sources had earlier told CBS News, the BBC's American media partner, that the US and Israel were planning what would be one of the harshest bombing campaigns to date against energy infrastructure targets in Iran.

The plan came up during Trump's cabinet meeting on Friday, sources told CBS News.

Trump further said in his post the US was "locked and loaded and ready to go against the Islamic Republic of Iran, at levels of Military Terror, Strength, and Power not seen since World War II".

He said cancelling the attack would be "for the future benefit of the world and, likewise, the survival of a successful and prosperous Iran".

Iran has not yet responded to Trump's announcement.

During the Friday meeting, CBS News reported Trump was heard saying while reporters were still in the room: "We'll be hitting them [Iranians] very hard. At some point, they're going to say, 'We just can't take it anymore.'"

Axios reported that Saudi Crown Prince Mohammed bin Salman spoke to Trump on Saturday and "expressed concern" about the potential strikes. Reuters also reported the phone call.

Washington and Tehran have engaged in escalating strikes and counter-strikes since a ceasefire in April aimed at pausing the war fell apart in June.

Earlier this week, the US said it completed a "heavy wave" of strikes against Iran in retaliation for an attempted ballistic missile attack on American forces in the region.

The US has blockaded Iranian ports and bombed Iranian sites, while Iran has fired missiles and drones at US assets in countries across the Middle East and targeted shipping in the Strait of Hormuz, a vital waterway for global oil shipping.

The US and Israel began launching their strikes against Iran on 28 February, with the outbreak of war leading to significant fluctuations in oil prices.