Mikel Arteta concedes Pierre-Emerick Aubameyang's challenge on Max Meyer in Saturday's 1-1 draw with Crystal Palace "looked nasty" but says there was no intention to cause injury.
The Gabon international received his marching orders in the 67th minute after a VAR review upgraded his initial yellow card to a straight red following his ugly lunge on the Palace midfielder.
Aubameyang had earlier given the Gunners a 12th-minute lead with his 14th Premier League goal of the campaign before Jordan Ayew ensured a share of the spoils with a deflected effort nine minutes into the second half.
Meyer was substituted immediately after the incident, but Arteta insists his player did not intend to injure the German.
"I just watched it and it looked nasty, to be fair," he told a media conference. "Knowing Auba, there's no intention to make such a tackle.
"Hopefully he hasn't been injured and we are sorry for that. The decision was made and we have to accept it."
Despite their numerical disadvantage, Arsenal came close to snatching all three points in the closing stages when Nicolas Pepe fired against the post.
While Arteta was happy with how his side responded to going down to 10 men, he expressed his frustration that Palace were allowed to find their way back into the game.
"I was pleased with how we started the game, with the way we dominated the first half," he added.
"But obviously after the break we knew they were going to push; they had more bodies forward and they put us under pressure more.
"We started to give bad free-kicks away and that's something that we have to avoid. Then we switched off for the goal. We completely switched off and allowed them to put the cross in. We turned and conceded the deflection, and I was very disappointed with that.
"After that, I must say that we reacted really well again after conceding the goal. After Auba's red card, we reacted even better in my opinion."
Palace manager Roy Hodgson agreed with Arteta's assessment that there was no malice in Aubameyang's challenge, but he did question why it took the officials so long to reach their decision.
"I knew it was a bad challenge," he said. "I'm not accusing Aubameyang of trying to injure him but when I saw it, it's no doubt that it's a red card. I was surprised it took so long to make the decision.
“He [Meyer] was upbeat after the game but we will have to wait until Monday to see if he can play in the next game."