The Gunners' setback against United over the weekend left them in eighth place in the Barclays Premier League following their worst start to a domestic campaign for 30 years.
But they bounced back in style at the Emirates Stadium by booking their spot in the knockout stages of the Champions League by seeing off their German opponents.
Yaya Sanogo scored inside two minutes, with Alexis Sanchez clipping home a sublime effort at the start of the second half to inflict a first European defeat this season on the Group D leaders - who could still be caught for top spot should results go Arsenal's way on matchday six.
Wenger said: "What is important is that we are united
"This team has a top-quality attitude and we have shown after the disappointment on Saturday that we were united in the game, determined, committed and after that people take what they like or don't like - we have to accept that
What's important is what we do inside the club."
The win came at a cost however, with Mikel Arteta limping off after a bad challenge midway through the second half
Wenger said the midfielder had "another calf problem and that looks quite serious", while Sanogo was clutching his hamstring as he left in the 79th minute.
But Wenger was full of praise for his compatriot striker, who missed the chance to double up only minutes after his opening goal.
Wenger said: "He played well
I decided to go a bit longer from the start and he protected the ball well and won many challenges.
"He's a young boy but he has presence, character and he's naturally committed
He has a natural, aggressive attitude up front that is vital and very important."
It is the 15th consecutive season that Arsenal will make an appearance in the knockout stages of the Champions League, which is an achievement in itself.
"I am very proud of that and I think the club also deserves a lot of credit for that
It's not enough because we want more than that, but we are consistent," Wenger said.
"From now until February we need to improve as a team, get encouragement from the game and then hope we have nearly all our players back in the next round.
"You see who is qualified around Europe and there are many teams who are at the top, top level
There are three or four teams you don't want to play."
Wenger admits it's "90 per cent (certain) Dortmund will finish first" in the group, but even with the glowing assessment, Jurgen Klopp says there will be no rest for the German outfit.
"We must work
Work always works in life," he said.
"We were just not courageous enough
We didn't close their players down and there were a thousand reasons why we were not good enough
But we will try to change this."
Source : PA
Source: PA