Guardiola highlighted their missing players as he tried to explain the collapse.
He said: "We do not expect opponents to not create chances and score goals. We're in the moment. We started really well, we had chances and after the first time they arrive we concede. Then it's a bit more difficult to come back.
"Chances were there. The moment they create the chances the build-up, we couldn't handle the duels like normally. Now we're struggling a little bit.
"It cannot happen. When you play top level teams we can concede chances but it's part of process. In our situation it's a bit tougher.
"I have to see the situation. The players came back late (from internationals). There were a few reasons we're not able to be consistent. Now the balance is not in the right moment. But it happened. We have to do it, talk and on Tuesday against Feyenoord have the chance to try.
"Of course Rodri is important but we knew that for many months. But (John) Stones can only play 45 minutes. Jack (Grealish) has been injured many times. Kevin (De Bruyne), two months and five months.
"We have to come back and freshen our minds. The season is so long. Many things can happen.
"Before the game I didn't know what will happen today. So I don't know what will happen at Anfield. Everyone knows the situation is new for us. We struggled more without the ball. I don't know how many chances we created. Our game was there."