The Frenchman has said he would be happy to sign for longer and has been convinced by Fulham that he is better staying with them as a first-choice striker than becoming a squad player at Old Trafford.
Coleman knows that Saha was flattered by interest from United and the episode unsettled him, but he will have no hesitation in playing him against Southampton on Boxing Day at Loftus Road and then at Aston Villa on Sunday.
The manager said: "Of course Louis will think about Manchester United. But he knows he's got a job to do for us. He hasn't thrown his toys out of the pram and he's more than prepared to stay and fight with the rest of us.
"We need to use this Christmas period to put two consecutive defeats behind us and Louis will be helping us to achieve that."
Fulham are set to be without midfielder Sean Davis (hamstring) for the Southampton game. Mark Pembridge (calf) is also out but Jerome Bonnissel (ankle) could return. Southampton are hopeful they will have Rory Delap (ankle) and Graeme Le Saux (hamstring) back.
Fulham v Southampton, Loftus Road, Boxing Day, 12pm