Real Madrid have long been admirers of both Manchester United winger Ronaldo and Arsenal midfielder Fabregas, while Barca are regularly linked with a possible swoop for Fabregas, who came through the youth ranks at the Nou Camp before his move to London.
Capello was speaking in the second part of an interview with Spanish sports newspaper Marca, in which he also discussed his views on the differences between coaching at domestic and international level.
He said: "There are big differences. One of which is very important - Real Madrid, Milan, the big teams represent a section of fans, to a large extent, but a national team represents all the fans.
"It is all the country behind you and this makes it very different."