The group held the meeting at Somnath Chowk in Mehsana, following which they tried to march to Dhanera in Banaskantha district. Mr Mevani planned the march to mark a year of the public flogging of four Dalit youth at Una by a mob on July 11, 2016.
The four youth, however, did not join the proposed public meeting. They also did not turn up at a gathering of Dalits from different parts of Gujarat in Ahmedabad on Tuesday to mark one year of the attack.
Police detained some 200 people, including Mr Mevani and Mr Kumar from Nani Dau village on Palanpur-Mehsana highway before the public meeting could take place. Police also filed a complaint against them.
Mr Mevani said his organisation, the Rashtriya Dalit Adhikar Manch, was not given permission to hold the rally allegedly under instructions from Deputy Chief Minister Nitin Patel, who is a resident of Mehsana.
The group planned to march to Dhanera, also in north Gujarat, and till the fields of Dalit farmers who were yet to be officially handed over land already allotted to them.