The Polish striker, who joined on a free transfer earlier in the summer following his departure from Borussia Dortmund, missed a number of chances on his debut and he admits that he expected to contribute more.
"We had a lot of chances to score," Lewandowski told reporters. "It would have been good to hit the net today, but luck wasn't on my side.
"I hope I can do better next time and the luck will be with me, because today there were a few chances where normally I'd put at least one of them away."
Defending champions Bayern return to Bundesliga action against Schalke 04 next Saturday.