Brazil international Silva, 28, helped PSG to the Ligue 1 title after signing from AC Milan on a five-year contract last summer but Barca are determined to strengthen their squad with a world-class centre-back ahead of a title defence.
Rosell is sure coach Tito Vilanova rates the player highly and would fully support a bid but is concerned PSG's cash-rich owners, the Qatar Investment Authority, would have no reason to listen to offers.
Speaking to Catalan television channel 8tv on Monday night, Rosell was quoted on Marca.com as saying: "Thiago Silva is a player we want - the board as much as the coach. When it comes to him, the price is not an issue.
"We are negotiating with people for whom money is not a factor. And if they're not willing to sit down and talk, we can't do anything.
"It's a matter of the player convincing them to come over here and start negotiating."