Grant Holt's first-half goal was enough to clinch all three points for the Canaries despite Arsenal enjoying the lion's share of possession.
Wenger was unhappy with his side's failure to create meaningful chances and admitted that it was their worst performance of the season so far.
"Norwich had a good defensive performance, were focused and committed. We had a lot of the ball, but did not create much with it, which was a disappointing performance for us," he said.
"I felt we lacked a bit of sharpness. We missed what makes the success at the top level, that is complete focus and they were sharper than us. We do not blame anybody, made many mistakes today. We have to put that performance behind us and realise that is not good enough.
"The attitude of the team has been excellent, but that was not at the level of what we have produced until now, it was the first time of the season we were way below par. We have to come out with a difference performance in the Champions League game (against Schalke) on Wednesday night."
The result leaves Arsenal ninth in the Premier League table, 10 points behind leaders Chelsea.