City were stunned 2-1 on Saturday at Dean Court.
Guardiola said afterwards: "We knew we couldn't match the intensity. We have talked about it. It was an open game. We had chances at the end but I congratulate Bournemouth for the victory.
"The 50-50 balls in the middle, the duels, they play this type of game. They are so aggressive. They had six-seven days to prepare. They have physicality and speed, but you have to win these types of situations. And they had chances. Ederson made a good save. We had real good moments at the start of the second half and after that it was difficult to swallow as we were good. After we scored we had momentum and chances but couldn't score.
"It is what it is. We have few players with a lot of minutes and a lot of players with no minutes to the balance is a bit uncomfortable. We played good against Spurs but today we could not handle their intensity that they had and that's why we lost the game."