The 27-year-old forward's deal with the Spanish champions runs out in 2015.
Portugal international Ronaldo has been the subject of speculation since he admitted to being "sad" for professional reasons in September last year.
The player has rejected suggestions he is looking for a move, although he did admit he does not know what the future holds beyond the end of his current contract.
Speaking to fifa.com in an interview conducted at last week's Ballon d'Or awards - at which Ronaldo was beaten to the top prize by Barcelona's Lionel Messi - the Madrid player said: "I want to see out my contract at Real: I'm very clear about that.
"After that, well, I don't know what'll happen in the future."