The Portugal midfielder has been linked with AC Milan this summer.
“I doubt Renato Sanches will go to Italy," Rummenigge told the Corriere dello Sport.
“If we do loan him out, it's just to ensure he plays consistently. We continue to believe in his quality, which is why we don't want to sell Renato. He's a good player, he's young and he needs time."
“There are many clubs other than Milan interested."