Calderon told a Spanish TV station: “We really like him but he belongs to Manchester United and they have to decide to sell him first.
“If that is the case then we’ll be first in the queue.”
Calderon insists Real will not consider making a £54 million bid for Ronaldo.
He said: “I don’t think any player, even someone with Cristiano Ronaldo’s quality, is worth that money, but we are definitely interested if Manchester United want to sell him.
“I would love to see both Kaka and Cristiano Ronaldo play for Real Madrid next season, but it won’t be easy. Any big club would have this sort of objective and Real Madrid is a big club.”
