TEHRAN, Iran — Iran is trying to put down a new wave of civil disobedience: flash mobs of young people who break into boisterous fights with water guns in public parks. A group of water fighters was arrested over the weekend, and a top judiciary official warned Monday that “counter-revolutionaries” were behind them.

Police swooped in to arrest a number of people who had gathered on Friday in a Tehran park to hold a water fight, the acting commander of Iran’s police Gen. Ahmad Radan said, quoted in newspapers on Monday.

Radan said the group had been planning the water fight through the Internet and had “intended to break customs.” He vowed police would act to prevent future attempts and that participants would be put on trial.

Throughout the summer, Iranian police have been cracking down. Dozens have been arrested in major cities around the country. Hard-liners see the water fights as unseemly and immoral, breaking taboos against men and women mixing.

Authorities worry that the gatherings could build into protests against Iran’s regime.