Guardiola has won two Champions League trophies - both at Barcelona - as manager, but he faces a tough task when he takes his team to Camp Nou this evening.
Iniesta, who spent four years under Guardiola's leadership, is confident that City will become a European heavyweight under the Spanish boss.
"I'm sure City can go and win the Champions League under Pep - I just hope it's not this season," The Mirror quotes Iniesta as saying. "This season, I want to taste victory in the Champions League again. It won't be easy, but that's the ambition. All the titles we want to win - to repeat the treble again would be special - and it's on our minds.
"City are top of what is one of the most competitive leagues in Europe, and that's where I think they will stay this season. They've started well under Pep, even if he's not been happy with the last two or three games.
"They will still be adapting to Pep's style of play and also he's only had one window to bring in his own players. They will continue to get stronger under Pep and challenge in both England and Europe."
City are unbeaten in Group C following one win and a draw, while Barcelona have a 100% win record so far.