City came from behind to win 4-1 away to Brighton on Sunday's final day of the season - a result that meant the reigning champions finished just a point in front of second-placed Liverpool, who won 2-0 at home to Wolves.
In most seasons, Liverpool's tally of 97 points would have seen them crowned champions.
Guardiola, celebrating his eighth domestic championship in 10 seasons that have featured La Liga and Bundesliga titles with Barcelona and Bayern Munich, was in no doubt about Liverpool's quality.
"We worked a lot," he said. "I have to say congratulations to Liverpool of course. Thank you so much. They helped to push us and to increase our standards from last season."
"To compete against this team pushed us to do what we have done. It's incredible, 198 points in two seasons."
"I think last season Manchester City made the standards," Guardiola added. "That is the level in the Premier League and Liverpool have helped us to be there all the time."
Guardiola's side secured exactly 100 points in winning the title last season but the manager was arguably even more impressed by their efforts this term, even if the overall tally was lower.
"To win the title we had to win 14 games in a row," he explained.
"For two to three months we cannot lose one point and we did it all playing in all competitions until the semi-finals of the Champions League.
"It's incredible. Normally if you get 100 points the tendency is to go down but Liverpool helped us to be consistent.
"This was the toughest title in all my career."
But Guardiola said next season could be even more competitive.
"It will be tougher but we will be stronger too," he said.
"When you can win two in a row I have the feeling that next season we will come back and try to be who we are right now."
Sunday's result meant Liverpool's wait for a maiden Premier League title - their last domestic championship was in 1990 - goes on, although they could yet win the Champions League if they beat Tottenham Hotspur when the English rivals meet in a Madrid final on June 1.
Liverpool forward Mohamed Salah, whose 22 goals this season made him a joint-winner of the Premier League's golden boot award, said the Anfield club would challenge again next term.
"We only lost one (Premier League) game all season," the Egypt forward said. "We gave everything. We got 97 points. We will fight next season for the title."