Milan have apologised to Inter for Gennaro Gattuso's decision to sing along with fans in an anti-Leonardo chant.
The midfielder took part in the derogatory chant about the former Rossoneri boss during the Scudetto celebrations at the Stadio Olimpico on Saturday night.
"As a club, I say sorry to Inter, President Massimo Moratti and Leonardo, a man I love as a friend," Milan Vice-President Adriano Galliani said.
The apology came after Galliani met with the Italian midfielder at the club's headquarters on Thursday afternoon.
"I gave Rino a shampoo," the official added. "He knows what I said to him, but I don't like to reveal private matters with others.
"Nevertheless, I told Gattuso that he made a mistake so let us now forget about this whole incident."
Leonardo was so offended by the abusive chant that he released a statement on the Nerazzurri's official website.
Moratti too also criticised the 2006 World Cup winner.
Gattuso and Leonardo had a difficult relationship last term while the Brazilian was in charge of the Milan side. He left at the end of the season and joined Inter in December.