The European champions and rivals Real Madrid have both been linked with a big-money move for the Portugal star.
Ronaldo, 21, signed a two-year deal in November 2005 that will keep him at Old Trafford until 2010 but has yet to agree terms on a new contract.
But Barcelona president Joan Laporta said he has too much respect for United to talk about moves for any of their players.
“I have good institutional relations with David Gill [United chief executive] and we have not made an offer for Cristiano,” he said.
“Of course, he is one of the best players in the world, he is young, he has a good projection. But we are very happy with the players in our team and we are not making any offer for any player.