Iran's police arrested 21,000 people during Israel's 12-day war in June, according to state media. They were detained as part of a campaign by Tehran to tackle Israeli espionage.
Police spokesman Saeed Montazeralmahdi said the public helped by reporting their suspicions to the authorities, Mehr news agency reported.
More than 260 people were detained on suspicion of spying while 172 were arrested for unauthorised use of video cameras and phones, Mr Montazeralmahdi said.
Iran last week executed a man convicted of spying for Israel. Roozbeh Vadi had passed on details of a nuclear scientist killed by Israel during the 12-day war, prosecutors said. He was found to have transferred sensitive information to a contact at meetings in Vienna and was paid with cryptocurrency, they added.
Israeli intelligence officials openly bragged about how easily Iran could be infiltrated.
Iran regularly announces executions of people convicted of working for foreign intelligence services. In June, Tehran executed three Kurdish men convicted of aiding Mossad in the 2020 assassination of nuclear scientist Mohsen Fakhrizadeh.
After Israel attacked Iran on June 13, Tehran pledged swift trials for suspects and has announced several executions for espionage.
Israel's surprise attack targeted Iranian generals, nuclear enrichment sites and scientists, and air defences. Iran retaliated by launching missile and drone attacks at Israel. Fighting stopped after US President Donald Trump announced a ceasefire on June 24.
Israel's strikes killed nearly 1,100 people in Iran, while Iranian strikes killed 28 people in Israel.
