Reports in Italy and England suggest the Premier League club have tabled a £63million bid for the Italy number one and are ready to offer him a five-year contract worth £12.5million a season.
However, Ranieri insists Buffon is going nowhere.
"Manchester City's offer for Buffon? Well if we wait a bit maybe the number of millions will reach 100," joked the former Chelsea boss.
"At the end of the season we could even reach 150!
"No, joking apart, Gigi remains with us. He will not go anywhere."
Earlier in the week, Buffon had claimed that while he would love to remain at Juve, he would be prepared to move for the good of the club if a big-money offer came in for him.
"At the moment a move is not on the cards," the 30-year-old said in a videochat with fans on Gazzetta TV. "Of course if someone offers 50million to the club I will be the first to the tell the directors to sell me.
"I want the best for Juve and with that amount they could reinforce the squad."
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