Iran, a majority-Shia nation, marked the end of the Islamic holy month of Ramadan a day after most other Muslim countries, which are mainly Sunni.
The Islamic republic's supreme leader traditionally leads the Eid prayers but Ayatollah Mojtaba Khamenei, who has not appeared in public since his appointment earlier this month, did not attend.
The head of the judiciary, Gholam Hossein Mohseni Ejei, however, attended the prayer at central Tehran's Imam Khomeini grand mosque named after the founder of the Islamic republic.
For lack of space, many worshippers followed the prayer outside, with state television showing images of crowded areas around the mosque, despite the risk of strikes.
The Iranian capital has come under near-daily bombardment since a joint US-Israeli attack started the war on February 28, killing top officials, including Mojtaba's father and predecessor Ayatollah Ali Khamenei.
Overnight strikes again targeted several districts of Tehran and its outskirts, as well as the central city of Isfahan, according to the Fars news agency.
Iranian television also showed prayer gatherings elsewhere in the country, including in Arak in the centre, Zahedan in the southeast and the western city of Abadan.
