The Germany legend has followed the lead of Uli Hoeness in condemning the Sweden striker for his outspoken comments
The Paris Saint-Germain striker played under the current Bavarians coach during his time in charge of the Blaugrana but fell out of favour at Camp Nou and left to join Inter in 2011.
And after Bayern president Uli Hoeness labelled Ibrahimovic a 'prima donna' for calling Guardiola a 'coward' in his autobiography, Rummenigge followed suit in hitting out at the 31-year-old.
"I would recommend to him to keep a sense of proportion. He's been previously convicted by Uefa," he said, referring to the ban Ibrahimovic was handed during last season's Champions League.
"That's gross unsportsmanlike behaviour. I would not do that if I were him, otherwise Uefa might consider this case. But maybe stupidity is part of developing your character."
Both PSG and Bayern are in Champions League action tomorrow night against Benfica and Manchester City respectively.