Dembele has been suspended indefinitely by Dortmund, having missed training without permission immediately after Barca had a bid for the 20-year-old France international rejected.
Dortmund CEO Hans-Joachim Watzke criticised Barcelona's role in the saga over the weekend, while Rummenigge's Bayern boardroom colleague Uli Hoeness condemned the Liga giants' conduct as "the lowest class".
But Rummenigge insists Dembele is ultimately responsible for his own actions.
"I do not believe Barcelona has called for Dembele to strike," he told Sport1.
"Perhaps the player just wants to change and has devised the plan himself. I would not condemn Barcelona too early."
Watzke and Dortmund's sporting director Michael Zorc have both confirmed Dembele will be sold if Barcelona meet the asking price, which is reported to be in the region of €130million.
Dembele joined Dortmund from Rennes last year for €15m.