Thousands of Iranians held Eid al-Fitr prayers on Saturday to mark the end of the Ramadan fast, as Tehran reported a strike on its nuclear enrichment plant and Israel threatened intensified bombardment.

Iran's supreme leader traditionally leads Eid prayers but Ayatollah Mojtaba Khamenei, who came to power earlier this month after his father was killed in a US-Israeli strike, has remained out of the public eye.

Instead, the head of the judiciary, Gholam Hossein Mohseni Ejei, attended prayers at central Tehran's Imam Khomeini grand mosque, which was filled to overflowing, with worshippers flooding the streets outside.

The previous evening, airstrikes had darkened the mood as the city celebrated Nowruz, the Persian New Year.

"The atmosphere of the New Year was spreading through the city. Places like Tajrish or Golestan Shahrak, where I went, were full of well-dressed and beautiful women buying flowers," said Farid, an advertising executive, reached by AFP through an online message.