The most expensive footballer in history has only two years left remaining on his contract with Madrid and United have explored the possibility of re-signing one of the most revered players of the Sir Alex Ferguson era.
Ronaldo was complimentary about his former club yet diplomatically expressed his contentment in Spain.
Ronaldo spent six years at Old Trafford
"I miss English football," Ronaldo said. "For me, it was some of the best years in my career when I was there in Manchester United. Everyone knows that it is a club that is still in my heart and I really, really miss. But now my life is in Spain. I am enjoying playing there, too."
Sir Alex Ferguson's retirement was a significant dent in United's chances of bringing Ronaldo back to Old Trafford, as the club's clout in the transfer market subsides in the wake of the Scot's departure.
New manager David Moyes has instead targeted Leighton Baines, but United had a £12 million bid rejected for the left-back by Everton last week.