Raiola was angry seeing Donnarumma jeered at Milan's San Siro stadium when turning out for Italy in their Nations League semifinal defeat to Spain.
He told Corriere dello Sport: "I'm disgusted by the boos against Gigio, and now I wonder why Milan didn't officially intervene to distance themselves from the dispute, to defend him somehow, after this banner appeared on a Milan bridge?
"Did he accidentally kill someone? I do not know. The truth is, Milan either didn't know him or couldn't keep him. Try asking anyone, what father would recommend to his son: stay in Milan or go to Paris Saint-Germain? It is very sad and shameful what happened at the stadium.
"It is shameful that supporters attack a boy who has done nothing wrong, whose fault is simply for having exercised his right to free choice. Because there is no other reason to boo him."