Reports in the German press claimed last season's Champions League finalists would sell the defender for £29.6 million next summer, but the club insists it is "nonsense"
The Germany international, 24, has long been linked with a move to the Spanish champions and a number of recent reports suggested that BVB are ready to let go of Hummels if a €35 million (£29.6m) offer comes in.
Watzke, however, has laughed off the rumours, telling ZDF: "That is absolute nonsense.
"This is a complete non-story. There's no truth whatsoever in these rumours."
Hummels, who has made 12 appearances this season for Jurgen Klopp's side, has a contract with Dortmund until June 2017.