The head of the march for the 45th anniversary of the November 17, 1973 Polytechnic Uprising with the students carrying the bloodstained flag of the Polytechnic reached the US Embassy in Athens at 16:30.
The protestors sang the national anthem, raised their hands over the flag and then folded it up and dispersed.
Meanwhile a separate protest march through central Athens was underway with the participation of student unions, organisations, parties, trade unions, leftists and anti-establishment groups that had gathered in Klafthmonos Square and made their way to the embassy.
Protestors shouted slogans condemning fascism, nazism and related ultra-right actions and beliefs.
Another march and a rally in Omonia is being organised by the Communist Party of Greece (KKE).
The city centre remains cordoned off to traffic, while the Megaro Mousikis, Evangelismos and Syntagma metro stations have been closed at the orders of the police.