City clinched the title on the final day by a single point thanks to a 14-match winning run.
"The fact we played these 14 games knowing if we draw a game or if we lose a game it will be difficult to retain the title," Guardiola said in an exclusive interview for This is Premier League, the review of the 2018/19 season.
The Spaniard said that the pressure from Liverpool, who ended the season with nine wins in a row, forced his players to raise their game.
"I think they helped us to be a better team, I am 100 per cent convinced on that," Guardiola said.
"The value of your title depends on the quality of your contender, your big rival, and I cannot find a better one than Liverpool."