The Ivory Coast-born striker, 18, was recently rewarded for breaking into the first-team at Selhurst Park with a new four-and-a-half year contract.
And Eagles co-chairman Steve Parish insists it will take a big offer to tempt the club into selling their prized asset.
He said: "He is a young boy who needs to keep his feet on the ground and we'll help him to grow and develop. He needs to mature as a player and there will be times that he'll need a rest.
"We haven't signed him for four-and-a-half years to sell in January. While you can never say never, if somebody rang us up and offered £12million you would have to think about it, but even then we'd say he's not for sale - that is the best message I can send out.
"He is a fabulous player and an integral part of our plans."