The Citizens have been largely unstoppable in this season's triumphant league campaign, but the Reds have beaten them three times in 2018.
Jurgen Klopp's charges were one of only two teams to beat City in the league while they also won both legs of their Champions League quarter-final.
"This season they were a big contender and they will be again next season," Guardiola told Sky Sports News.
"I will not say just Liverpool, but it's true - Liverpool, [because of] the way they play and the quality of their players, not just up front.
"I think [Virgil] van Dijk has helped them a lot to be more consistent in the defensive department, especially in the box, and [there is] the quality up front and the quality in the way they play.
"Jurgen is a top manager, creating not just an offensive style and not just thinking about the spectators. He's always positive, going there and creating good environments in the clubs.
"OK, we are 25 points in front so it's difficult to say he was difficult [to play against] in the end - but he was because they beat us."
Liverpool last won the English top-flight title in 1990.