The Bayern Munich chief is adamant the midfielder is a huge part of Pep Guardiola's plans and says Toni Kroos, Thomas Muller and Holger Badstuber are the club's future
The midfielder, 29, has not been ever-present in the first team since Pep Guardiola's arrival, although much of his absence is explained by injuries, the latest of which is set to keep him out until January.
Despite speculation over Schweinsteiger's role in the first team under Guardiola, Sammer is adamant that the Germany international is indispensable to the Bavarians.
"Bastian is essential for this club as a human being, personality and player," he told TZ when asked whether the midfielder's position was under threat to the likes of summer signing Thiago Alcantara.
"Sure, he has to physically return to top shape, but he is one of our leaders. His place in the team is without question.
"As a key player he has to face the competition, there's no question about that. He must indeed confirm his claim to the position. But to discuss about Schweinsteiger with disapproval is disrespectful and vile."
Sammer also discussed Bayern leaders on the pitch and suggested Holger Badstuber, Toni Kroos and Thomas Muller are being groomed as potential successors to Philipp Lahm's captaincy.
"Thinking of a new captain is not an issue for the next two years, but this is our biggest challenge," he added. "Our leading players at the moment are Philipp Lahm, Bastian Schweinsteiger and Manuel Neuer, while Dante has become a top player too.
"Muller and Kroos I'm looking at as being in an exciting stage of development, in addition I also hope that Holger Badstuber comes back strong. This Bavarian trio - Muller, Kroos and Badstuber - will be the next big Bayern generation."
Bayern face Raja Casablanca in the Club World Cup final on Saturday.