Malaga have warned Manchester City that they will have to meet Isco's £17m release clause in order to bring the player to Eastlands.
The Premier League champions have been linked with a move for Spanish midfielder, who has starred in Malaga's impressive start to the La Liga season.
However, the big-spending outfit are keen to retain Isco's services and have insisted that they will not be forced into selling their star asset.
Malaga sporting director Mario Husillos told tuttomercatoweb.com: "He is our player and is important for the team. He is not on the market.
"We want to keep him here but you all know there is a buyout clause in his contract. So, if a club pay the clause, it does not depend on us anymore."
Juventus are also thought to be admirers of the 20-year-old.
