The Spanish coach has insisted the Gunners should not have conceded such cheap goals against the Hammers.
West Ham took advantage of Arsenal’s slow start to the London Derby to hit three goals past the visitors inside the opening 32 minutes through strikes from Jesse Lingard, Jarrod Bowen and Tomas Soucek.
The Gunners swiftly mounted a comeback when Alexandre Lacazette’s shot took a ricochet off Soucek to beat Lukasz Fabianski on 38 minutes.
Arsenal benefited from another own goal from Craig Dawson midway through the second half to cut their deficit before Lacazette completed the comback eight minutes before the final whistle.
Speaking after the game, Arteta was not impressed with how his men started the game.
He told Sky Sports: “I'm very disappointed because I cannot accept my team to play the way we did in periods in the first half. I expect we play at the level we did afterwards.
"The first goal, it can happen. It is a really good combination [by West Ham]. That is fine. The way we concede the second and third is unacceptable. Afterwards the attitude and togetherness we showed - it is really difficult to do what we have done. We got really close to winning and I think we deserved to win it but the first part really worried me."
The Spaniard complained about Arsenal’s setup during set piece, he added: "Unacceptable. We talk about that all the time. I don't know if it's a hangover from Europe, tired, focus, it was more than one player that switched off. We have to right that quick."
