Iran's Supreme Leader Ayatollah Ali Khamenei accused Donald Trump on Saturday of lying when the US president said during his Gulf tour this week that he wanted peace in the region.

On the contrary, the United States uses its power to give '10-ton bombs to the Zionist (Israeli) regime to drop on the heads of Gaza's children', Khamenei said.

Trump told reporters aboard Air Force One after departing the United Arab Emirates on Friday that Iran had to move quickly on a US proposal for its nuclear programme or 'something bad's going to happen'.

His remarks, said Khamenei, 'aren't even worth responding to.'

They are an 'embarrassment to the speaker and the American people,' the Iranian leader added.