The 25-year-old feels his lack of a clinical edge this season has cost his side on occasion but insists the number of chances being created by the team is encouraging.
The Poland international currently leads the Bundesliga goalscoring charts with 11 goals from 16 games, yet he has admitted that he could easily have added more to his tally.
"Am I happy with my own performances so far? No, not at all. I might have scored 11 times, but I should have scored many more goals," Lewandowski was quoted as saying by Bild. "I cannot say how many more, but I should definitely have scored a few more goals."
Lewandowski added that he alone was not to blame for Dortmund's lack of cutting edge at times this season and insisted the number of chances his side has been creating was an encouraging sign.
"That's not just my problem, but a problem for the entire team as well. We did not drop so many points because we played badly, but because we have missed a lot of chances," continued the 25-year-old. "We must become even more eager in front of goal. On a positive note, we create a lot of chances. It would be a bigger problem if we did not create anything."
Dortmund currently sits third in the Bundesliga table with 32 points from 16 games.