Forest lost 3-2 at City Ground so leaving new manager Ange Postecoglou winless over his first six games in charge.
However, Forest chiefs believe Postecoglou's team suffered at the hands of referee Willy Delajod and his linesmen.
Delajod booked only one FCM player – wing-back Kevin Mbabu – but handed three yellow cards to Forest: Morato, Igor Jesus and Morgan Gibbs-White.
Forest were left unimpressed, given the physical approach of FCM on the night. They also were unhappy with the way Delajod consistently held up the game when momentum was with the hosts.
As such, Forest have now made a complaint to UEFA, reports the Daily Mail.
