The Brazilian has been the long-standing number one at Camp Nou, but has recently expressed his desire to end his 18-year Barca career when his contract expires at the end of the season.
Reports have claimed that the Spanish outfit have already identified Pepe Reina, currently on loan at Napoli from Liverpool, as the 31-year-old's replacement, but Rosell has revealed that Barca have not given up hope of convincing Valdes to stay beyond his current deal.
"I have tried to convince him to stay but I cannot tell you that we have met as yet," Rosell told reporters.
"Of course, I have tried and he has not yet come off. I will certainly be trying again. We have a year left and that is a long time."
Valdes has made 364 appearances for Barcelona's first team since debuting in 2002.