Forest suffered a 3-0 defeat to Derby away from home at the iPro Stadium in the Championship on Sunday afternoon.
Nicklas Bendtner put the Rams in the lead after just 33 minutes when he scored an own goal.
Tom Ince doubled the home team’s advantage 10 minutes into the second half, and Will Hughes wrapped up the scoring with the third in the 64th minute.
Former Forest defensive midfielder Moussi, who is 31 years of age, has taken to Twitter to give his reaction to the final result.
Moussi has expressed his disappointment at the defeat for the Reds, but he has backed them to bounce back.
Philippe Montanier’s side will return to action on Wednesday evening when they take on Preston North End at the City Ground in the Championship.
Feel for the boys cause they prepared hard for that game. Head up there is a game Wednesday at the city ground and they will respond— Guy MOUSSI (@Guy_Moussi) December 11, 2016
Forest are 16th in the Championship table at the moment with 25 points from 20 matches, five points above the relegation zone.