Barton attacked PSG defender Thiago Silva in a series of tweets this week.
Marseille issued a statement on club website om.net apologising for Barton's remarks and promising an immediate end to the episode.
It read: "Olympique de Marseille and Joey Barton are keen to apologise to Thiago Silva and his club for the inappropriate comments made by the English player on social networks during the past 36 hours.
"This morning, the management asked Joey Barton to put an end to the attack on PSG's Brazilian defender. The Marseille midfielder pledged to immediately cease the posting of anything derogatory about Thiago Silva."