But Dortmund stalwart Weidenfeller was not happy with the way Dembele conducted himself as he sought the transfer, believing his behaviour to be "ridiculous".
"That's not the way to leave a club," the goalkeeper told ESPN of Dembele's departure. "It caused an unbelievable unrest and nobody could calm down.
"This is a team sport - football is not tennis. He did not even take his boots [before leaving] - it's ridiculous. Before, I could not imagine that there is such a thing.
"Dembele was given the opportunity to make a name for himself at Dortmund at the age of 19. Here, he developed into a player that Barcelona wanted to buy.
"But instead of being grateful, he left the club, staying at home, striking and letting his team-mates down. That's just bad style - no manners."
Dembele suffered a torn hamstring in just his second Barcelona appearance and has only now established himself as a regular at Camp Nou, scoring twice against Villarreal on Wednesday.