According to Yahoo! Sport, Bonucci is on the radar of United with AC Milan potentially being required to sell players in order to fulfil their obligations with Financial Fair Play.
At the weekend, a report claimed that UEFA remained unsatisfied with Milan's financial situation and that the Italian giants faced expulsion from the Europa League and a fine in the region of €30m (£26.46m).
Owner Yonghong Li is said to be searching for outside investors but if that proves to be unsuccessful, Milan could be forced to raise funds by selling members of their first-team squad.
Club captain Bonucci made 48 appearances during his first campaign at San Siro.