Guardiola was reacting to last night's 3-2 home defeat to Real Madrid in the first-leg of their Champions League round 16 playoff.
The Catalan said: "It's all of us – not the players. I have no problem accepting that it doesn't work the way it did before.
"For me it would be easy to blame a specific player, but it is ridiculous and does not help. It is first and foremost me and also the players.
"They really want it. See how they run and do it, but the truth is that we are not stable enough in these situations, because this was no exception. It has happened many times."
The Spaniard added: "I've been here for many years and we've been an extraordinary team, a machine every three days. This season, I have to accept that the opponents are better, but in these situations I'm not good enough to give the team the peace to deal with it."