Despite leading twice through Erling Haaland, City were undone by late goals from Brahim Diaz and Jude Bellingham.
Guardiola admitted the loss was tough to take, especially after controlling large parts of the match.
“It’s the fourth time we played in a row against Madrid here and in the three previous we were much, much better than them but today was tight and in certain times they had chances and Ederson was our best player,” Pep reflected post-game.
“Sometimes it happens that a team is better and the result doesn’t work.
“I think they started well for 15 minutes and after we took the game and we were really good with the ball.
“In the second half, we could not make the passes that we needed to play. We wanted to attack so quickly but when we attack so quick with the strikers that they have it’s more difficult.
“After it was 2-1 but it happened too much this season. In many games it happened, against Feyenoord, Sporting Lisbon, Brentford in the Premier League Man United, many games we gave away.
“We have to look at ourselves and at this level it’s so difficult. It’s not the first time unfortunately it happened many times and that’s why it’s so difficult.”