The Gunners tasted defeat for the first time this season when they went down 2-1 at the Emirates Stadium.
"We have conceded three goals from three set-pieces in the last two games that cost us points and it is not got enough," Arteta said. "I don't think it is something to do with the defence, it is to do with an individual set-up in the game, which is a free-kick or a corner or whatever, and we haven't defended the ball well enough and we conceded three goals in those two games."
Both goals were preventable, as Fernando Torres outmuscled Laurent Koscielny to hook in Juan Mata's free-kick before the the former Valencia midfielder's second-half delivery was allowed to creep inside the far post after Gervinho had pulled the hosts level just before the break.
While the France international did not cover himself in glory for either goal, his slight deflection helping Mata's free-kick past Vito Mannone's dive, Arteta insists every one of the Arsenal players must stand up and be counted.
Arteta added: "You cannot blame one player, you have to clear the lines so quickly and you cannot allow runners like that in the box, and it was the same sort of ball for both goals.
"It hurts when you lose points at home against teams like that and you feel you haven't deserved to lose."
Arteta, though, insists Arsenal can take confidence from their start to the campaign.
"We have played some of the best teams in the league and we haven't been battered at all. In fact it has been the opposite, we have been better than them through the 90 minutes. I think that is a very positive thing," he said.