Fonseca was angry over Charles De Ketelaere's opener, which he felt was scored via a foul on Theo Hernandez. Alvaro Morata found an equaliser for Milan before Ademola Lookman found La Dea's winner.
“In the second half, we didn’t get the ball to the forwards enough, leaving Rafa (Leao) and Morata isolated,” Fonseca told Sky Sport Italia.
“At the end of the day, we lost the game on two set plays. The first half was very good, but in the second we didn’t have that link with the strikers. I think we deserved more tonight, it was tough to accept conceding two goals from dead ball situations.”
Fonseca continued: “I have always been quiet about the referee, but others talk. Today I am the one who am tired of staying quiet and watching what happens. The first goal was a clear foul, there are absolutely no doubts. The way the referee officiated throughout was against Milan, there are no doubts.
“It’s not even just today. I recognise that refereeing is a tough job, but I am tired of watching the same decisions go the same way against certain clubs. With other clubs, they have no doubts, but with Milan they always do this. There is no respect towards Milan.
“I am not afraid to speak the truth. I always respected the work of the referees, I realise they have a difficult job, but every week it is always the same. They lack respect for Milan. The way the referee officiated throughout this evening was a lack of respect for Milan.
“That foul changed the game, we were in a losing situation to a goal that should’ve been disallowed. It upsets me that I am forced to talk about the referees, but I am revolted by this situation. It happens every week.”