Some 20 Gonabadi dervishes were reportedly detained in the northeastern Iranian city of Gonabad on July 23, RFE/RL's Radio Farda reports.
Sources close to the Gonabadi dervishes told RFE/RL that 200-300 dervishes were protesting in front of Gonabad's judiciary building against the jailing of Hossein Zareyi -- who is in charge of a dervish cemetery in Gonabad -- when they were attacked by riot police and security forces.
The police reportedly used force and tear gas and some dervishes were injured in the clashes.
Zareyi was arrested earlier this week over the burial of a dervish at the cemetery.
Authorities had banned dervishes from being buried at the cemetery for what they claimed are ecological reasons.
But the dervishes say the ban is part of a government campaign against Sufis that has intensified in the past four years that President Mahmud Ahmadinejad has been in office.
The leaders of the Gonabadi dervish order have lived and been buried in Gonabad for more than a century.
Several conservative clerics in Iran have described Sufis as a cult and a "danger to Islam."