"The National Ethics Committee has handed a two-match suspended ban to Joey Barton for 'inappropriate comments' after his tweets about a Paris Saint-Germain player," OM said on their website.
Barton, who has more than two million followers on Twitter, used the microblogging site to insult Thiago Silva last month. He also made disparaging comments about some of the PSG player's international team-mates.
PSG had threatened action against Barton whose comments also drew condemnation from gay activists.
Thiago Silva did not respond to the tweets.
"The remarks he made towards Thiago Silva were not homophobic remarks. They were just out of place," Ethics committee president Laurent Davenas told Reuters TV.
Barton arrived in France on loan from Queens Park Rangers after a colourful career in England.
He spent two-and-a-half months in prison for assault after a night out in Liverpool when he was already on bail for attacking former Manchester City team mate Ousmane Dabo.
He also stubbed out a cigar in the eye of a youth team player in 2004.
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