The Ahmedabad Police registered the case in connection with the roadshow held in Bopal area.
"Hardik, who heads the Patidar Anamat Andolan Samiti (PAAS), and his supporters were booked under IPC section 188 for disobeying the police order," Bopal Police Inspector I H Gohil said.
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Hardik and his supporters, who were on their bikes, had organised a roadshow on December 11, despite being denied permission by the district authorities, he said.
"Today, we have lodged an FIR against him and 50 other bikers for disobeying the police notification," Gohil said.
This is the first FIR against Hardik after the state Assembly elections.
Three days before the second phase of Gujarat Assembly polls, the rally-cum-roadshow on motorcycles and cars was organised, which started from Bopal and culminated at Nikol area on the other end of the city, covering a distance of around 15 km.
While Bopal area falls under the jurisdiction of rural police, Nikol area is under the city police limits.
After the roadshow, Police Commissioner A K Singh had expressed displeasure over Patel's move and said that legal action would be taken for holding the event without permission.
Singh had denied permission to Prime Minister Narendra Modi and Congress chief Rahul Gandhi to hold roadshows in the city during the campaign which the leaders of the two parties had obeyed.