Fellaini has been offered terms by Milan as he comes off contract at United.
“Fellaini could be an important player, he is," Mirabelli said.
“We know he is not going to renew with United, but it's difficult to say that we have closed the deal.
“He has important attributes. We will do something in that role but we are keeping everything in reserve.
“First we have to secure our signings, then announce them."