Real have often expressed their desire to lure the Manchester United winger to the Bernabeu and despite United insisting he is not for sale, Ronaldo's declarations following Portugal's Euro 2008 exit could mean a move is on the cards.
However, while admitting it would be a great coup to land the Portugal star, Calderon insisted the transfer is far from a done deal.
"As we have already said many times, it is a problem between Manchester United and the player," Calderon told Spanish sports daily AS.
"If the two resolve this situation and Manchester United want to call us then we will be happy and delighted with them because Cristiano is a great player.
"We can't say anything more, we only talk about our own footballers and Cristiano is Manchester United's."