Despite having plenty of the ball, the Gunners - who included England midfielder Jack Wilshere in the squad after more than a year out with injury - were lacklustre as Grant Holt's scrambled effort on 20 minutes following a mistake by keeper Vito Mannone proved enough for all three points to move the hosts out of the relegation zone.
"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."