The marchers gathered shortly after 18.30 in front of the Presidency on May 9.
They said they supported Ukraine in the war started by the Kremlin and expressed dissatisfaction with the Bulgarian Parliament's refusal to help Kiev with weapons. In their view, Ukraine should be supported right now on Europe Day because it is also support for peace.
They also expressed dissatisfaction with the position of President Rumen Radev, who is against providing military aid to Ukraine.
The procession marched through the central streets of Sofia and blocked the traffic shouting "This is not Moscow" and then the demonstrators headed to the Russian Embassy. Around 22:00, they were urged to return to the Soviet Army Monument.