US President Donald Trump has said the strikes obliterated Iran's nuclear programme, but the full extent of the actual damage remains unknown.

Iranian President Masoud Pezeshkian, in a visit to the country's nuclear organisation, said Tehran "will build (the destroyed sites) stronger than before".

"By destroying buildings... we will not be set back," he said in a video posted to his official website, adding that Iranian scientists still had the necessary nuclear know-how.

Pezeshkian did not elaborate. In similar remarks in February before the strikes, he said Tehran would rebuild its sites if they came under attack.

Israel launched an unprecedented bombing campaign against Iran in June, kicking off a 12-day war that saw it target nuclear and military facilities -- as well as residential areas -- and kill many top scientists.

Iran retaliated with ballistic missile barrages aimed at Israeli cities.

Iranian Foreign Minister Abbas Araghchi said in July, after the United States announced a halt in fighting, that the damage in Iran was "serious and severe".

Pezeshkian's comments came as Oman, Iran's traditional intermediary, urged the two countries on Saturday to resume talks.

"We want to return to the negotiations between Iran (and) the United States," Omani Foreign Minister Badr Albusaidi said at the IISS Manama Dialogue conference in Bahrain.

Iranian government spokeswoman Fatemeh Mohajerani said Sunday that Tehran "has received messages" on resuming diplomacy, without providing further details.

Oman hosted five rounds of US-Iran talks this year. Just three days before the sixth round, Israel launched its strikes against Iran's nuclear facilities.

Iran has since faced the return of UN sanctions after Britain, Germany and France triggered the "snapback" mechanism over Tehran's alleged non-compliance with the 2015 nuclear deal.