Mikel Arteta's 60th minute spot-kick, given after Jean Beausejour was adjudged to have felled Theo Walcott, proved the decisive moment in a very tight game played in sodden conditions.
Wenger said: "They organised to stop us playing and they did that very well, especially in the middle of the park. We didn't find the same fluency going forward and it was much more a win because we wanted the result than because we dominated the game."
It earned Arsenal a third successive Barclays Premier League victory for the first time since March.
"It's good but it's not enough, you want more," added the Frenchman.
"I hope that gives us a bit more belief and confidence. We have a week to prepare for the next game and hopefully at home we can continue to win our games. It's an important part of the season now."
Walcott was again given his chance up front after impressing in the role against Reading and Wenger gave the England man qualified praise.
He said: "I wouldn't like to judge him on one game but he has the ingredients to play there. He didn't have much service, he was a bit isolated but he can always be decisive. Again he made the decision and he got the penalty."