Iran's supreme leader warned on Wednesday that the Middle East war would widen if America resumes its attacks, dismissing hopes of a policy shift in Washington after midterm elections dealt a blow to US President Donald Trump.

Trump has recently threatened to renew the war against Iran amid similar rhetoric from Israeli Prime Minister Benjamin Netanyahu, but on Tuesday he suffered a resounding defeat in polls that will strip his Republicans of control over Congress.

The results, which Tehran says is a repudiation of the war, could constrain Trump's ability to enact his agenda, though the president retains the power to order new strikes.

"Those who still harbour even the slightest hope that the behaviour of the hegemonic system might change through partisan or factional shifts, or who imagine that making concessions to the United States can dissuade it from hostility towards the Iranian nation, are seriously mistaken," Iranian supreme leader Mojtaba Khamenei said in a written statement Wednesday.

He also warned that if the United States did choose further military action, the scope of the war would widen, without elaborating.

Khamenei has yet to appear in public since he took power in March following the killing of his father and predecessor in US-Israeli strikes, and has communicated through written messages.

Earlier, Mohammad Bagher Ghalibaf, Iran's chief negotiator in talks with the US, said Americans had voted against war in the midterms.

"Conscience or the cost of living, Americans said NO TO WAR, and we endorse this message," he posted on X.

"If the US govt betrays their public will to serve international paymasters and blackmailers, it will learn our NO comes with a Nightmare," Ghalibaf said.

Iran's judiciary chief Gholamhossein Mohseni Ejei also hailed the election results, saying Trump had been "defeated both militarily and politically".

The war has proved unpopular among the US public, who have seen the cost of living rise after a spike in energy prices caused by the war.

Trump on Tuesday acknowledged the conflict may have played a part in the defeat of his Republican Party.

"I think a part of it was Iran, but at the same time, people understood the importance of what I've done," Trump told Fox News.

On Tuesday the US launched strikes on Qeshm Island in the Strait of Hormuz, with Iranian state media reporting five explosions in rapid succession.

"They built an anti-aircraft facility... As soon as it was completed, we hit it last night very nicely," Trump told US media, but he called it a "minor attack". (AFP)


Edited by Aaron Tam