Iranian authorities warned young people against using the traditional fire festival as the starting point for various revolutionary activities. The counter-revolution infects youth to perform sensational acts, says Tehran province judiciary chief Ali-Reza Avaie.
Charshanbe Soori, an ancient pre-Islamic festival, is held on the eve of the last Wednesday of the Iranian calendar year and is often seized as an opportunity to protest -- implicitly or explicitly -- against the government.
This year, the ritual falls on the night of March 15.
The festival is a prelude to Nowrouz, the Persian New Year which starts on March 21 and marks the arrival of spring.
Iranians celebrate the occasion by lighting bonfires in public places and leaping over the flames shouting, "Give me your redness and I will give you my paleness," with red symbolising good health.
Opposition websites warned some three weeks ago they would incite street protests on the day of the festival if the isolation imposed on opposition leaders Mir Hossein Mousavi and Mehdi Karoubi had not been lifted.
But the sites issued no fresh protest calls on Monday.
Last year, Iran's supreme leader Ayatollah Ali Khamenei urged Iranians to shun the festival as an un-Islamic event which causes "a lot of harm and corruption" and has no "basis in sharia", Islamic religious law.
Police also cautioned parents against the use of dangerous firecrackers by their children as each year hundreds of people are injured in accidents.
Ahead of the festivities, the police announced the seizure of more than 10 tonnes of fire crackers and hazardous flammable and explosive devices.