City were hammered 4-0 on Saturday, marking a fifth consecutive defeat for the champions.
Guardiola later said, "We are fragile at the moment, we could not defend properly. We started well, struggled to score and then conceded. Then situation is more difficult.
"I’ve been here as a player, maybe not as a manager, first three games at Barcelona we lost. The only chance we have is stay there. Last eight years the results have been there, it would be a mistake to change the approach.
"There are not fairytales in life and sport, sometimes you have to live through these situations. You have to accept it. You can't blame each other, stay together, continue to do what we have done.
"Run away? Absolutely not, we have to stand up more than ever. What will define us is when we fail, we stand up and face it.
"I don’t know what will happen this season, but not for one second will I not believe in these players. There is no team in the world that can sustain success for eight, nine, ten years in a row.
"Of course everything is not fine, but what we try to do is analyse it, let’s go to next game and see what happens."