At least 36 members of the outlawed Hizb-ut Tahrir group have been arrested across the country since Friday.
They include Saiful Islam, a key organiser of the group, which was banned in 2009 for an anti-state campaign.
Police have launched a nationwide search for the members of the group who took part in the banned rally outside the Baitul Mukarram National Mosque in Dhaka.
Private security personnel appointed as auxiliary police for Ramadan, Eid: DMP
"We are analysing the video footage of the rally. We have identified many members of HT, and they will be arrested for joining a political program of a banned organisation," Chief Adviser's press wing said quoting Inspector General of Police Baharul Alam on Saturday.
Police have filed several cases under anti-terrorism laws against the members of the group.