"Stoke are showing an interest in the player," Phil Sproson told The Sentinel. "But they will have to buy because Villa won't loan him.
"They are looking to sell him in this window if they can, or in the summer if not, but Marlon's contract runs until the end of next season.
"Villa will listen to realistic offers, but if someone tries to nick him it will not happen. It's a case of whoever strikes a deal with Villa first will probably get him."
However, Sproson claims Harewood - who left West Ham in 2007 - is not looking to leave Villa Park.
"He's not in a fantastic rush to leave Villa, but he is missing not playing regularly and is at that stage of his career where he wants to be playing," added Sproson.
"But he understands the situation at Villa. They are a top-five club now and the standard there is unbelievably high. There are England players in front of him in the team."