Wagner's side have now lost to Chelsea and City in their first two matches of the new Premier League season, and the German has urged the Terriers to now start their campaign at home to Cardiff City next weekend.
"In the end, it wasn't a tactical decision which decided the game, it was just the quality we faced today. With the problems we had before the game, it didn't make it easy for us and we have to say congratulations to City for a great performance, we were not good enough today," Wagner told Sky Sports News.
"For us now, the season starts. We hoped for more out of these two games, we could not expect more from these two games even if we didn't want to have a heavy defeat like today, but now the season starts.
"We're focused, we won't get too upset from this result, the good thing is we had this last season where we lost heavy defeats and the character of this group is to move forward."
Huddersfield finished 16th in the Premier League table last season - four points clear of the bottom three.