The Welshman was sent off for the first time in his career against Besiktas, having picked up two yellow cards, but the Arsenal boss disputed the decision after the 0-0 draw.
The Wales international was dismissed in the 80th minute for picking up a second yellow card after tangling with Oguzhan Ozyakup and Wenger was furious with the decision after the game.
"We could have won it but they had chances as well. In the end we didn't lose and hopefully we will make it at home," he told ITV. "Both yellow cards for Aaron Ramsey are unbelievable. When you see the fouls they have made today, it's not serious. Just not serious.
"It was a game played with a frenetic pace. We didn't lose the game and hopefully we'll finish the job at home."
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The dismissal — the first of Ramsey's career — means he will be unavailable for selection when Besiktas travels to the Emirates next week for the deciding leg of the tie.
Wenger also took time to praise Calum Chambers after the 19 million euro signing from Southampton turned in an assured performance in his European debut.
"I think he was once again very good and convincing in his performance," he added. "He coped with the pressure and coped with the challenges of a pitch that, overall, was not easy. I think he has done extremely well."