The Germany international endured a largely disappointing campaign in 2016-17, failing to net double figures for goals in the Bundesliga for the first time in five years.
With Bayern boss Carlo Ancelotti on the search for new attacking recruits, Muller has been warned that he is at risk of losing his place on a regular basis if he does not improve his goals tally.
"He'll have to play a stronger season," Rummenigge told Muncher Merkur. "The competition is also strong in his position. I wish him a strong season and a lot of goals."
Bayern have already missed out on at least one of their summer targets, as Sandro Wagner extended his deal with Hoffenheim until 2020 on Sunday morning.