Ferran Torres struck a brace and goals by Ilkay Gundogan, Gabriel Jesus and Rodri helped City record a thumping result against a lacklusture Arsenal side.
Arteta's side have now lost all three of their Premier League games this season without scoring a goal.
An embarrassing 2-0 defeat against Brentford was followed by a loss by the same scoreline against Chelsea. A 6-0 League Cup thrashing of West Brom eased the pressure slightly, but talk of the Spaniard's future is now back in the spotlight.
His team have managed just seven shots in their first three games. They recorded just one effort against City but it failed to test City goalkeeper Ederson.
Pep Guardiola backed Mikel Arteta after Man City smashed Arsenal 5-0 (Image: GETTY)
Ultimately, the result left Arsenal bottom of the league with zero points and a humilitation -9 goal difference.
However, Guardiola - who had Arteta as an assistant at City for nearly four years - has backed his long-term friend to turn Arsenal's results around.
"All I can say is that we worked for two or three years together. What I learned from him... I could learn many, many things," Guardiola told BT Sport.
"He's a very good manager. He has the correct personality and he is the leadership qualities.
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"He's incredibly loved by all of us [at Man City]. We were sad when he left.
"Sometimes people expect the results immediately. The squad today that he played is not the squad that he dreamed."
Guardiola pointed out that Arteta is missing some key players.
£50million centre-back Ben White has missed their last three games as he is recovering from COVID-19. Thomas Partey has not featured this season after limping off against Tottenham in pre-season.
Arsenal boss Mikel Arteta is under pressure after his Man City humiliation (Image: GETTY)
By comparison, Guardiola is only missing midfielders Kevin de Bruyne and Phil Foden.
"He has so many players injured. Six, seven or eight injuries," the Spaniard continued.
"Really important players missing. Ben White and examples like that. Thomas Partey isn't here.