Iran's supreme leader Ayatollah Ali Khamenei on Thursday said US President Donald Trump "exaggerated" the impact of US strikes on his country's nuclear sites, in his first appearance since a ceasefire in the war with Israel took hold.

In a statement and a televised speech carried by Iranian state media, he hailed his country's "victory" over Israel and vowed never to surrender to the United States, while claiming that Washington had been dealt a "slap" after striking Iranian nuclear sites.

Khamenei's remarks come two days after a ceasefire ended a 12-day war between Iran and Israel, the foes' deadliest and most destructive confrontation in history.

It also follows a stinging row in the United States over the actual extent of the damage inflicted by American strikes on key Iranian nuclear sites during the conflict.

"The American president exaggerated events in unusual ways, and it turned out that he needed this exaggeration," Khamenei said.

The United States "has gained nothing from this war," he said, adding that American strikes "did nothing significant" to Iran's nuclear facilities.

"The Islamic republic won, and in retaliation dealt a severe slap to the face of America," he said, a reference to Iran's missile launch targeting the largest US base in the Middle East.

"I want to congratulate the great Iranian nation... for its victory over the fallacious Zionist regime," he added, claiming that Israel had "almost collapsed" because of Iran's strikes.

Both Iran and Israel had already claimed they won, with Israeli Prime Minister Benjamin Netanyahu hailing on Tuesday a "historic victory" for Israel.

Meanwhile, US Defense Secretary Pete Hegseth on Thursday said he was unaware of any intelligence suggesting Iran had moved any of its highly enriched uranium to shield it from US strikes on Iran's nuclear programme over the weekend.

"I'm not aware of any intelligence that I've reviewed that says things were not where they were supposed to be, moved or otherwise," Hegseth said. (AFP/Reuters)