Mensah was sent off in the 3-0 defeat to Olympique Lyon two weeks ago after receiving two yellow cards.
He is reported to have used abusive language on referee Tony Chapron who had booked him for a tackle.
Mensah’s action earned him a second yellow card.
The 23-year-old began serving the suspension against Ajaccio last Sunday and will miss the matches against Montpellier and Lille.
He will be available for selection in the away match at Bordeaux on 22 February.