The southern French port city hosts the La Plaine event every March. But this year's unauthorized party was also partly a protest against continued coronavirus lockdowns and restrictions on movement.
Police in Marseille used tear gas to break up a crowd of thousands who took part in an unauthorized carnivalon Sunday in breach of coronavirus lockdown rules.
The southern port city usually hosts the La Plaine carnival every March, but last year's event was canceled due to the outbreak of the global pandemic.
France Bleu Provence, a local radio station, reported that as many as 6,500 people attended the gathering in the city.
Seven arrests were made after one group threw projectiles at police.
Dozens of €135 ($160.5) fines were handed out to those who refused to wear face masks.
Romain, a-26-year-old attendee, said that "young people are fed up with being under lockdown."
"There are no frail elderly people here, only young people," he told AFP.
The mayor of Marseille, Benoit Payan, lashed out on social media at "the selfish attitude" of the party-goers, branding their behavior "unacceptable."
"Nothing justifies destroying our collective efforts to contain the virus," he said.
French law says that organizers of any protests or public rally must inform local authorities at least three days before it is due to take place.
But officials said they were unaware that the anti-lockdown event was set to take place.
Marseille and the surrounding area is not affected by the new shutdown restrictions that came into force on Saturday.
The new lockdown will be in place for at least four weeks in 16 departments, including the Paris region and the nearby Alpes-Maritimes.
France is one of the European countries that looks set to be hit hard by a third wave of coronavirus infections.
Public Health France warned on Sunday that intensive care admissions were at their highest since the end of November, with more than 4,400 COVID-19 patients currently in ICU.
jf/sri (AFP, dpa)