The Gunners' last hope of silverware this year lies in Europe's elite competition, after suffering exits in the FA Cup and Capital One Cup running alongside a constant struggle to challenge for the Premier League title.
The North London side also face a real fight to claim a place in the top four during the current campaign, and the Spaniard insists that their season has not been good enough.
"The Champions League is massive," Arteta told ESPN. "If we don't get in those [top four] spots, then it makes everything much more difficult. To any team with top players, you have to ask what's going to happen in this answer and there's only one answer: we want to improve the team.
"The line between being good and bad is really thin. It's not easy for anyone, not the manager, the players or the staff. We have a very good team but we are missing that little thing which makes a difference.
"That's where we need to find the key, but with 10 games to go, it's an impossible catch [the title chasers] and that, for me, is not acceptable. I think everybody knows that. I think the board knows that and hopefully this summer we'll do something about it."
Arsenal currently trail Bayern 3-1 after the first leg of their last-16 encounter.