Nine people arrested during an anti-vaccination rally on Saturday in the northern port city of Thessaloniki were released on Monday.
They have been charged with multiple crimes, including attempting to cause physical harm, resisting arrest and disturbing the peace.
Eight of the nine received an extension to prepare their defenses.
The ninth is a minor and will be tried by a juvenile court.
The nine were among a group of protesters who attacked police while trying to force their way through a security cordon into the Helexpo conference center where Prime Minister Kyriakos Mitsotakis was giving his keynote speech at the opening of the Thessaloniki International Fair.