The political council of 17 parties held a second day of protests, demanding Prime Minister Nikol Pashinyan to step down.
The participants gathered near Matenadaran at 5 pm, demanding to lift the martial law and calling on Prime Minister Pashinyan to resign.
The protesters then marched to the National Security Service, demanding to release the detainees.
Four more participants have been detained on suspicion of organizing a rally in violation of the law.
The protests will resume tomorrow at Freedom Square at 4pm.
The unrest is triggered by the signing of a Russian-brokered statement to end the war in Nagorno Karabakh.
The joint statement envisages the handing over of three regions to Azerbaijan.
Peacekeeping troops of the Russian Federation are being deployed along the line of contact in Nagorno-Karabakh and along the Lachin corridor linking the Republic of Artsakh to Armenia.
The parties have agreed that a plan for the construction of a new route along the Lachin corridor shall be determined within the next three years, providing communication between Nagorno-Karabakh and Armenia, with the subsequent redeployment of Russian peacekeeping troops to protect this route.
The Republic of Azerbaijan shall guarantee traffic safety for citizens, vehicles and goods in both directions along the Lachin corridor.
All economic and transport links in the region shall be unblocked.