Mancienne has had two successful loan spells at the club, and spent the whole of last season at Molineux. But McCarthy would rather re-sign the midfielder, who can also play in the centre of defence, on another loan deal rather than buy him outright.
Chelsea want to sell the player after he handed in a transfer request.
McCarthy said: "I would like to see my quote where I said I would be prepared to pay £4 million. I am pretty good at remembering what I said but I am red hot at remembering what I haven't. We won't be buying Mancienne. They want to sell him. If they want to loan Michael out again, then that's a different matter altogether.
"I haven't discussed it with Chelsea. From my understanding, they want to sell him and he's asked for a transfer. They want to sell him rather than loan him. I would be interested if they want to loan him out again but that's up to them.''