The German goalkeeper has announced his intention to leave Borussia Monchengladbach at the end season, with Camp Nou widely tipped to be his destination.
Valdes' contract at Barcelona expires at the end of the season and Ter Stegen is seen as a possible replacement for the departing 32-year-old, though Bartomeu acknowledged the 21-year-old is not the only option the team is considering.
"I can't say too much," the president told beIN Sport. "It is true that he's one of the keepers that we've followed, but we've also looked at others. There are a lot of good goalkeepers, but we have the best in the world here. What is unfortunate is that he has decided to leave the club next season."
Ter Stegen has made 18 appearances in the Bundesliga this season, keeping six clean sheets to help Monchengladbach rise to fourth in the table.