Guardiola has won five major trophies since taking charge at the Etihad Stadium in 2016, including two Premier League titles.
As yet, however, they have been unable to transfer their domestic dominance onto the European stage.
City have not yet progressed beyond the quarter-finals under Guardiola, getting knocked out by Monaco, Liverpool and Tottenham in the Spaniard's last three campaigns.
Guardiola won the competition twice at Barcelona but could not repeat that at Bayern Munich. His tenure at the German club was consequently considered a disappointment in some quarters, despite him winning three successive Bundesliga crowns.
He said: "We will, of course, not just be judged on the way we play but the titles we win. That is the truth. It is as simple as that. Last year was an extraordinary one for us but people say, 'But you didn't win the Champions League'.