The Gunners have suffered defeats by City in both the league and FA Cup already this season and Arteta expects another "difficult" game.
Arsenal, who last won the Premier League in 2004, drew 3-3 against bottom-placed Southampton on Friday, after squandering two-goal leads against both West Ham and Liverpool.
"If we win tomorrow we have not won the league. It will shift probably the percentage, but five games in this league is very tricky still," he said.
"We knew we had to go to Etihad, it will be difficult, but will it decide the season? No," Arteta added.
"The belief is there, I look at how the players reacted after Southampton, they defend each other in every moment. We really want it and we are again going to show it tomorrow night."
Guardiola said his former assistant had helped take the Gunners to "a different level".
"Arsenal have always had incredible details about keeping the ball, the players they select for the club have big quality and skills," he said.
"Mikel [Arteta] has brought them to a different level; they are so competitive and aggressive."
Arteta confirmed midfielder Granit Xhaka, who missed the Southampton game with illness, is a doubt for the fixture, while centre-back William Saliba has shown "no real improvement" in his recovery from the injury he sustained in the Europa League penalty shootout defeat to Sporting Lisbon in March.
BBC