City are in control of the last-16 tie ahead of the return leg on March 15, but at several moments during the first leg their European destiny appeared to be hanging by a thread.
Guardiola's side went ahead, fell 2-1 and then 3-2 down, but finally rallied with three goals in the last 19 minutes from Sergio Aguero, who scored a brace, John Stones and Leroy Sane.
"A lot of things happened, but in the moment we were lucky. We were stable mentally," Guardiola told BT Sport at the Etihad Stadium.
"The old and young guys in the team played amazing. To live this experience helps us a lot in the future.
"Monaco has more history than us in the competition and you need this kind of experience to learn and improve.
"Of course anything can happen in Monaco and we have to score goals. We think in attack: attack, attack, attack."
He added: "The result is OK. It could be better, could be worse, but it is what it is."
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