"Real Madrid is not just about photos and advertising, we are a football team and we know that we have to win games and earn titles. I'm sure Beckham is just going to concentrate on the football," Carlos told the Spanish sports daily Marca.
"Beckham is a great player and he is going to strengthen our team.
"What I want to happen is that in the first game he plays he is the best, so that everyone gets to see that he is an excellent footballer.
"That way all the comments about him being a mere publicity machine will end."
Beckham, who joined Real from Manchester United last month, is viewed by many commentators in Spain as surplus to requirements at Real given the club's surfeit of quality midfielders.
The signing of the England captain is, however, seen as a key part of the club's strategy to strengthen its image, particularly in the all-important Asian market.
But Roberto Carlos said he believed once the season got underway the former Manchester United player would be judged solely on the strength of his footballing talents.
"At the moment everyone is talking about how good-looking and how nice he is, but when he starts to play all that will change," he said.
