The 21-year-old has been loaned out to Sampdoria and Queens Park Rangers during the last two seasons, with competition stiff for a place in a star-studded United attack.
"For Federico, it's very difficult to break through here, it might be better that that he leaves in January," he told Itasportpress.
"He wants to play more and if that cannot happen at United, then we must find a solution.
"I'm with Sir Alex this week and I hope he understands the situation, it makes no sense to keep a 21-year-old striker on the bench."
Macheda has been in impressive goalscoring form for United's Under-21 side in the early weeks of this season, leading to rumours of a loan move to Watford.