Balotelli's future at City has been in question throughout January and reports in Italy suggest Milan remain interested in the player.
While the Serie A club have been priced out of a permanent deal for the 22-year-old, there have been fresh reports he could move on loan to the San Siro.
But Mancini insists there has been no approach for his compatriot or any other members of the City squad as he prepares his players for Saturday's FA Cup tie at Stoke.
Mancini said: "It is not true, Mario stays here. We didn't have any requests about Mario or other players."
Mancini has maintained this firm line on the possibility of Balotelli leaving the Etihad Stadium, even after a training-ground bust-up with the player earlier this month.
Milan are interested in the forward with vice-president Adriano Galliani issuing regular statements on the possibility of a deal but the club are unwilling to meet City's reported £28million valuation.
Galliani has urged City to lower the price but Mancini says he has no intention of letting his former Inter protege leave, even on loan.
When asked if Balotelli was part of his long-term plans, Mancini said: "Yes, Mario has another three years on his contract."
Mancini was speaking at a press conference to preview his side's FA fourth-round tie at Stoke.
The Balotelli subject was the first to be discussed and Mancini said: "For two years, the first question is always Mario!"
The transfer window closes next week but Mancini is not anticipating much activity.
He said: "I don't know but we don't have enough players. We are 18 players now. We can't sell any players."
When asked on the possibility of players coming in, Mancini said: "I think it is difficult."