Mansa police said the First Information Report was registered against Mr Patel and his associates including Dinesh Bambhaniya and Atul Patel under IPC sections 143 (unlawful assembly) and 188 (disobedience to order promulgated by a public servant).
The FIR was registered by executive magistrate Mahesh Soni on November 20, police said.
According to Mr Patel's supporters, police asked them to change the venue if they wanted permission for the rally.
His supporters didn't agree and went ahead with the rally at the planned venue.
The event, "Adhikar Sabha," saw a huge turnout.
Mansa is the home town of BJP president Amit Shah.
Hardik Patel, who is heading Patidar community's agitation for reservations, today declared support to the Congress for the Gujarat Assembly elections, saying that the opposition party has accepted the demand of reservations.