The Red Devils had been linked with a £16 million move for the Germany international, with Louis van Gaal keen to rebuild a central defence that lost Rio Ferdinand and Nemanja Vidic in the off-season.
But Klopp has laughed off suggestions that he could lose the World Cup winner, as well as attacker Marco Reus, and is confident the duo will remain at Signal Iduna Park.
"I can assure you that there are no signs that one of them wants to leave us," the BVB boss told Ruhr Nachrichten.
"Mats joining Manchester United? For €20 million (£16m)? For such little money you can forget that immediately!"
Van Gaal included Hummels on his six-man shortlist for summer targets before officially taking the role last week.
Meanwhile, United chief exectuive Ed Woodward has told fans to "watch this space" as Van Gaal looks to bolster his squad ahead of the new season.
Luke Shaw and Ander Herrera have both already arrived at Old Trafford, while Goal understands Juventus star Arturo Vidal and Everton midfielder James McCarthy are also targets.