Massimiliano Allegri's men have slipped to 10th in the Serie A table and won just two of their last nine matches in all competitions.
Milan's slow start means qualification for the UEFA Champions League appears unlikely, with the San Siro outfit needing to dramatically improve if they are to challenge for a top-three finish.
Despite the result, Allegri expressed satisfaction at his team's display and wants to see more of the same against Fiorentina.
"We have to keep working and putting in this sort of performance," he told Sky Sport Italia.
"The side played well in terms of technique and defending, but we lost our unity a little after the equaliser and allowed a couple of dangerous counter-attacks.
"After going 1-0 up we didn't take some more chances, but then with this goal we were caught out after a corner and got punished."
Fiorentina enter the fixture in sixth place following a 2-1 home defeat to Rafael Benitez's Napoli on Wednesday.
That was the club's first defeat in seven matches, ending a run of form that included a come-from-behind 4-2 victory over reigning champions Juventus.
Fiorentina have lost just one of their seven competitive away games this term and boast the league's top scorer in Giuseppe Rossi.
