Buffon said that the club cannot grow and begin to compete with the best in Europe by getting rid of their best players.
"[Letting] a player like Pirlo [go] is never up for discussion," Buffon told Sky Sport Italia.
"If we started to do that, then we may as well dismantle the stadium bit by bit, go home and stop playing football. I hope that we never deprive ourselves of such a strong player."
Buffon has been capped 136 times by Italy.