A stalemate at the Estadio do Dragao made sure the Citizens became winners in Group C with one game left.
Guardiola thinks the Premier League side have done really well in Europe so far.
“Congratulations to my team for this game and finishing first. We played to win, we didn't concede a shot on target or a corner all game,” the Spanish coach told reporters after the game.
“Alongside Benfica, Porto are one of the best teams in Portugal, very physical. We did really well but unfortunately couldn't score, all the players were fantastic.
"We struggled to score against Porto but we played really well with incredible personality and many things about the game were brilliant."
He added: "Absolutely very happy - it's more than the results, we played really well in all the games. 11 shots on target against Olympiakos and against Marseille as well and today we had lots of chances.”
“Maybe not as much today but enough to win clearly but the way we played, the courage and defensively we were so good."
Manchester City will now turn their attention to the Premier League as they welcome Fulham to the Etihad Stadium on Saturday.
