The Citizens are undefeated in all competitions so far this season and have only failed to win one game in 2017-18, a 1-1 draw at home to Everton in August.
In addition to their results, the team has scored 42 goals in 13 games so far, and conceded just six, but Guardiola believes that a blip is due at some point.
"We are in October. We cannot expect to finish the season like we have done in the last month when we won all the games," the Spaniard told Sky Sports News. "It's impossible in football in the high level.
"But I want to see how we are going to react in that moment when we drop points. We will see how strong we are because teams always show in the bad moments. I'm optimistic because the way we reacted at 3-2 against Stoke was so good."
Up next for the Citizens is a Premier League home encounter with Burnley on Saturday.