However, when asked about those rumours, Sammer insisted that the 27-year-old is an "incredibly important" part of the playing squad at the Allianz Arena.
"No-one needs to start knocking on our door about Mandzukic. He is incredibly important to Bayern," he told Sky Deutschland.
"I always affectionately say that he plays like an animal. It is simply amazing how much work he does for the team and how much running he does during a game. They always try to provoke him because he really hurts his opponents with his workrate."
Mandzukic has scored 22 goals for club and country this season.