"It's difficult for our mood not winning and, yeah, that can happen," the Spaniard told reporters. "But maybe we will improve for the future on that, to realise that sometimes it's not enough what you've done to win games.
"I came here in the first half to try to do what we've done all season, but maybe it's not enough to win at Champions League level or the Premier League."
City, who remain 13 points clear in the Premier League, have conceded six goals in their last two matches, with Liverpool scoring three in 19 minutes at Anfield in the first leg of their Champions League tie last Wednesday.
Similar lapses in concentration have cost Guardiola when he was in charge of Bayern Munich, with Real Madrid scoring three in 18 minutes in the second leg of a Champions League semi-final in 2014.
The German side also lost to Barcelona 3-0 in the first leg of the semi-final the following season, despite the game being goalless after 77 minutes.
"I thought many times about that... I've dropped a lot of Champions League games in the space of 10 or 15 minutes," Guardiola added.
"Maybe it's my fault. I have to think about it. But I feel that when you dominate and create chances you are closer to winning games and I think this season showed that."
(Reporting by Hardik Vyas in Bengaluru)
