Fellaini's contract at Old Trafford expires in June, though United manager Jose Mourinho has remained confident that the Belgium international will remain in Manchester .
However, the 30-year-old could be set for Italy after Mirabelli hinted at a transfer as he praised the towering midfielder.
"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."
Fellaini made 16 appearances – 11 from the bench – as United finished second in the Premier League this season.
Altogether, Fellaini featured in 23 games – starting seven – across all competitions.