Arsenal suffered a shock defeat in Croatia against Dinamo Zagreb in their Champions League opener and had to play much of the game with 10 men after Olivier Giroud’s first-half red card.
The Frenchman was booked for dissent before receiving a second yellow card from referee Ovidiu Hategan for a challenge on Dinamo right-back Ivo Pinto, a decision Wenger said he didn’t understand.
“I believe the first goal was offside and then afterwards the sending off was very harsh,” Wenger said.
“The first yellow card was Giroud’s fault because he protested, even if there was no foul against him. After that he should have not protested to the referee.
“His second yellow card was completely unlucky to touch the guy. I do not understand the referee.
“I don’t think he saw the guy. It was completely accidental. It happened and I think at that moment it was not a second yellow.
“It has to be a foul on purpose and it was not on purpose. The referee should have given several yellows based on that.
“It’s difficult because we had a lot of the ball and we had early chances. We were a bit unlucky.
“We have to look at ourselves as well because the second goal killed our game. We are good enough to defend corners like that well.
“Apart from that we had a lot of the ball when it was 10 against 11. They were committed, they defended well and sometimes I felt that they stopped us from gaining an advantage without being punished by the referee, especially on counter-attacks where we had to play 10 against 11 in one half.
“We were not at our best but neither was the referee.”