Reports have appeared throughout recent months suggesting Madrid would attempt to prise Rooney away from Old Trafford, with former president Ramon Calderon claiming last month that they were "obsessed" with signing the England striker.
However, Sir Alex Ferguson dismissed the continued rumours as part of the "silly season" this week and said: "Wayne will be here next year."
Rooney is understood to be closing in on a new contract at United and Ronaldo, who said in October that it would be "lovely to see him here one day", has now admitted his former team-mate would not welcome a move to the Bernabeu.
"I am still friends with Wayne Rooney, Rio Ferdinand and Nemanja Vidic at Manchester United," he told the News of the World. "I think Rooney is very happy in Manchester and, even if Real Madrid tried to sign him, I don't think he would want to join me here."
Despite Ronaldo's ongoing friendship with Rooney, he feels he was justified in helping to get him sent off when England played Portugal at the 2006 World Cup.
Rooney was dismissed for a stamp on Ricardo Carvalho, with Ronaldo leading the protests to the referee and then winking to his bench following the red card.
"I must be honest, if the same thing happened with England and Wayne Rooney that happened in 2006, I would do the same," he said. "I didn't do anything wrong.
"I just defended the colours of my country. That is all that I did and I feel fine about what happened."
"He is a very important coach, one of the best in the world," he said. "He has done a fantastic job in England and has won many titles in Italy, so why not? You never know."
Ronaldo had earlier said he would be happy to see Jose Mourinho take charge of the club.