Riot police used tear gas to disperse PAOK Thessaloniki supporters who on Monday had gathered to celebrate the club's 94th birthday despite the coronavirus lockdown.
More than 200 PAOK fans broke a government ban on public gatherings outside the club's Toumba Stadium due to the Covid-19 outbreak in the country.
Local media reported that at least one supporter was arrested and a number of others were fined following the clashes.
Government officials announced on Monday that 2 245 cases of the coronavirus have been detected so far in Greece with 116 deaths, and a ban on sporting activities is in force until at least 27 April.
Earlier on Monday Greek deputy minister of sports Lefteris Avgenakis said that he believed the country's professional football clubs would begin training again next month.
"We will wait for the advice of the experts and based on their instructions we will start to gradually to open sports facilities," Avgenakis told Mega television.