Police arrested Zurab Japaridze, one of the leaders of the Coalition for Change, on the morning of December 2.
A video was released showing Japaridze being dragged into a police car.
His whereabouts are currently unknown. The party leaders are trying to determine where he was taken by the police.
The detention was preceded by a confrontation between police forces and protesters.
Protesters blocked the road with barriers made up of public and private property- bins, benches, scooters, umbrellas and road signs – to protect themselves from the brutality of the special forces. Police detained several protesters using excessive force.