The champions were far from their best but still proved too strong for the manager-less Terriers at the John Smith's Stadium on Sunday, winning with goals from Danilo, Raheem Sterling and Leroy Sane.
Victory cut Liverpool's lead at the top of the table to four points and City have now scored 102 goals in all competitions this season, but Guardiola still expects more.
"Today we are happy we have won but immediately we have to analyse what we have done and to win in the future we have to play good," he said after the game.
"During the season you have games when maybe you are not in the top level and it is important to win these games. All the teams have that but to arrive in the last stage of competitions our game will have to improve."
Asked how he could expect his side to get better, Guardiola said in his post-match press conference: "Our pace, more passes in a row - we were not able to make a lot of passes. Always in football when you play good you have the ball as much as possible."