US President Donald Trump said the Isfahan, Natanz and Fordo facilities were "obliterated" in the strikes on Sunday and told Iran's leaders that they now had a choice of "peace or tragedy".
Iranian officials have confirmed the facilities were struck but denied it had suffered a major blow.
Iran's ambassador to the UN accused the US of "waging war" under an "absurd pretext".
Meanwhile, Israel continues to strike Iran, saying it's hitting military targets.
