The goalkeeper refuses to discuss new terms and has just over a year to run on his current deal.
Bartomeu told Catalunya Radio: "We have been in contact with Valdes to make it very clear that the doors are still open to him staying at the club.
"Because we prioritise footballing matters, we'd rather keep Valdes until the end of the 2014 season than sell him this summer.
"We don't have a deadline for the Valdes affair. One option would be for him to see out his contract - in which case we wouldn't sign a keeper."