More than a dozen people were reportedly injured and at least 70 others detained during clashes with riot police in Athens on Monday night.
Police fired tear gas at groups of youths who hurled stones and plastic bottles while burning US and EU flags.
All but 10 of the detained were later released.
The unrest followed an earlier mass protest marking the 1973 student revolt against the then military junta.
About 40,000 people took part in the annual protest which has become a focal point for Greek anger at current government policies including cuts under a an EU bailout.
The US comes in for special criticism, being accused of backing the 1967 -74 military dictatorship.
People also placed wreaths and flowers on a memorial at the Polytechnic University where dozens are believed to have died in the revolt.