They have exploded improvised bombs and vandalised vehicles before locking horns with the law keepers, police say.
At least 50 people were arrested over Friday afternoon's clashes on the Shaheed Shahidullah Kaisar Road.
Additional Superintendent of Police Saiful Haq said JCD activists exploded several crude bombs from a procession.
They vandalised about 20 vehicles and several shops before police intervened.
The JCD activists also blocked the Dhaka-Chittagong Highway at Mahipal and vandalised several vehicles there.
Police fired several blank shots and teargas canisters to disperse the agitators.
The situation was brought under control after around an hour, ASP Haq said adding traffic on the Dhaka-Chittagong Highway had resumed.