Banned for three matches for slapping an opponent against Napoli earlier this month, Ibrahimovic has already served two games and must now sit out Saturday's meeting at San Siro.
"The decision of the appeal court of the soccer federation is unjust because it has applied a sanction designed for violent acts to an act which was not violent," A Milan statement said.
"It is a grave error of judgement."
Milan have though slipped up in other big matches this season - losing to Inter Milan, Napoli, Lazio and Barcelona - while Juve's problems have been against smaller sides, drawing with Cagliari, Parma and Siena since the start of the year.
Milan centre-back Thiago Silva expects victory for Massimiliano Allegri's outfit.
"It's an important challenge. I am happy with the squad, we have rediscovered our will to win," the Brazilian told Milan Channel.
Buoyant Napoli, who beat Chelsea 3-1 in the Champions League on Tuesday, host down-at-heel Inter Milan on Sunday with Claudio Ranieri's team having taken only one point from their last 15.
