Hundreds of anti-war protesters rallied peacefully in central Athens as U.S. Secretary of State Marco Rubio arrived for talks with Greek leaders, but police stopped them from marching to the U.S. Embassy.
Student groups, unions and far-left parties gathered at the University of Athens gateway in the afternoon, then tried to head for the embassy.
Police blocked the route. The rally ended shortly before 9 p.m., and streets closed for the protest were reopened.
Two smaller anti-war rallies were held in the northern city of Thessaloniki, including a separate march by anarchist groups.
Mr. Rubio is in Athens to lead the American delegation at the sixth Greece-U.S. Strategic Dialogue, the first time a sitting secretary of state has done so. Authorities banned public gatherings and motorized marches across central Athens for 24 hours from Wednesday morning, deploying thousands of officers.
Protests have long accompanied senior American visitors to Athens, where anti-U.S. sentiment on the left runs deep.
When Secretary of State Condoleezza Rice visited in 2006, several hundred leftists marched toward the embassy and were also stopped.
The annual Nov. 17 march marking the 1973 uprising against Greece's military junta ends at the embassy and has occasionally turned violent.
Demonstrators objected to American involvement in the wars in Ukraine and the Middle East, which loom over Mr. Rubio's three-country tour of Iceland, Greece and Portugal.