The 18-year-old declared earlier this summer that he does not intend to sign a contract extension with the Rossoneri, meaning that he could depart as a free agent in less than 12 months' time.
Buffon has offered some guidance to his heir apparent, telling him to simply do what feels right when it comes to taking the next step in his career.
"I don't give advice, because I always made my own mistakes and would only be adding further chaos to the situation," he told Sky Sport Italia.
"I did have a bit of a 15-minute chat with Gigio, though. I can't tell you what we said. I have no idea if he'll remain at Milan, but I merely tell him to do what makes him happy."
Manchester United and Real Madrid are also reportedly keen on Donnarumma, who is due to meet with Milan chiefs in the coming weeks to discuss his future.