City, who relinquished the league title to Liverpool, lost 1-0 at Southampton on Sunday despite dominating possession (73%) and peppering the Saints goal with more than 20 shots.
Striker Che Adams sealed victory for 13th-placed Southampton and condemned City, who beat Liverpool 4-0 in their last game, to a third successive league defeat away from home.
Champions Liverpool have lost twice in the league all season.
“We’re leading in goals. We create a lot of chances,” said Guardiola, who lost a third straight away league game for the first time in his managerial career.
“We’re a team who concede less — no team conceded as few chances as us but we lost a lot of games.
“It’s difficult even for me to find a reason why but you have to insist and talk about the game, the way they play and try to do more, concede as few as possible and score up front.”
Guardiola backed City to return to winning ways at home against Newcastle United on Wednesday.
“I have confidence we can do it because we are the same guys and we did it in previous seasons,” he added.
“This season the way we are playing is quite similar but it is not enough to win the games.”