The Senegalese striker has been linked with a move to Turkish giants Fenerbahce in recent weeks.
“Mamadou is at the club and he will be staying here,” Dassier told AFP.
“I’ve spoken to Didier (Deschamps) on Saturday evening and the message can’t be any clearer: it is out of the question to sell (Niang) only a week before the league start up again.
“We are not in the selling market, especially as we haven’t received any offers.”
