Mendy laid on assists for both Raheem Sterling and Bernardo Silva as an under-strength City spoiled Unai Emery's first match in charge of the Gunners.
A cruciate knee ligament injury meant the France left-back had a minimal impact on the field during his first season in Manchester but his inimitable work on social media established him as a cult hero with City's fans.
It is a status that has not gone unnoticed by Guardiola, who observed the 24-year-old popping up all over Emirates Stadium on Sunday.
At a post-match news conference, when it was put to Guardiola that Mendy sometimes appeared to be more like a centre forward, he chuckled: "Yeah, and that is not good!
"Mendy is Mendy. Sometimes you want to kill him and sometimes you say, 'wow, what a player we have'.
"He gives us this extra energy. With Kyle [Walker] and him, when they attack so consistently it is so important.
"But Mendy has a lot of things to improve. Hopefully we can convince him to be calm, to forget a little bit the social media and focus on what he has to do."
When City tweeted the quotes from their manager, Mendy was quickly contrite – replying "Oops" and, "I promise I will".
City are next in action on Sunday as they host Huddersfield Town in their opening home game of the campaign.