The Bavarian giants are currently 17 points clear at the top of the Bundesliga table, have reached the DFB-Pokal semi-finals and are 3-1 up from the first leg of their Champions League last-16 tie against Arsenal.
"We are optimistic and hopeful to win the league holding such a lead, but, doing the maths, we have neither won the league nor the cup," ESPN quotes Rummenigge as saying. "We will treat our next games with the utmost respect.
"Dortmund will remain our biggest rival for a long time. They have good management, a good coach and good team. Maybe we will meet again in the Champions League.
"[General manager] Uli Hoeness believes we will win the Champions League within the next five years, and I also believe we have this chance. Maybe we are ready for it this year. I'd wish that for [coach] Jupp [Heynckes]. Even if he wins the treble, we would only have luxury problems."
Bayern lost to Chelsea on penalties in the final of the Champions League last season.