The German was not present in the match-day squad for Wednesday's EFL Cup win over Leicester City.
The club's highest-paid player insists he is not leaving the club this summer, but it is hard to see how he will get a game under Arteta.
The Spaniard told reporters: "You can see that the players we are changing, we are using, it's very difficult every week not for Mesut but for some other players as well to make the squad. Every week we try to pick the right players.
"It's difficult for others as well that aren't involved in the Premier League and didn't play tonight either. We have a squad of 26, 27 players at the moment and we can't give playing time to all of them.
"I understand [the questions] but I have to do my job as straight as possible. I select the players in the best condition."
Asked why Ozil had fallen out of favour, Arteta said: "The team is evolving, you can see the level they are achieving. This is where we are at the moment. We want to evolve more and play better and compete better.
"We need to keep maintaining that."