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 top Serie A with 50 points and 48 goals scored from 24 games but Juventus, who have conceded 14, are one point behind and have a game in hand.
Juventus have subjected champions Milan to two of their six defeats in all competitions this season, winning 2-0 in Turin in Serie A in October and 2-1 at San Siro in the first leg of an Italian Cup semi-final earlier this month.
Since then, Milan have returned to winning ways with a 2-1 win at third-placed Udinese, a 4-0 demolition of Arsenal in the Champions League and 3-1 win at Cesena.
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.
Inter suffered further misery on Wednesday with a 1-0 defeat at Olympique Marseille in their Champions League last16 first leg.
Udinese, third with 42 points, visit Bologna in another Sunday evening game when fourth-placed Lazio complete a turbulent week at home to Fiorentina.
Beaten 5-1 at Palermo on Sunday, Lazio coach Edoardo Reja offered his resignation on Wednesday but it was turned down by the club.
