Benzema has attempted to play down suggestions of an imminent departure from Lyon as they seek a seventh consecutive French title.
He claimed previously that he would only leave after helping Les Gones to the Champions League title, but he has admitted his head would be turned by an offer from the likes of the Old Trafford club.
"Milan make me dream," he told Italian sports daily Gazzetta dello sport.
"Also because Ronaldo is there - he's my idol. He's from another planet.
"But I also love Juve, Inter and Manchester United - the big clubs. What's important is to win.
"I would leave Lyon only to continue to win and when I also feel ready mentally."