"City look like the best team in the world, that's how it is," Klopp told reporters.
"Barcelona struggled a little bit (against Villarreal on Tuesday) but still did the job. Juve look pretty impressive in Italy but you don't exactly know how it will be in the Champions League if Cristiano Ronaldo cannot do it.
"And you think, OK, City look a bit more stable than all of them. But that doesn't mean they will win all their games."
While focus has been on City seeking a clean sweep of silverware, the prospect of Liverpool's themselves completing a Premier League and Champions League double seems to have slipped under the radar.
Klopp, however, does not expect his players to take their foot off the gas until the end of the campaign.
"I'm just interested in our games and we cannot do more than win our games," the German manager added.
"We knew pretty quick Southampton was the next challenge, then Porto, then Chelsea, then Porto again. There is a lot to come and the only thing I can say is that we try everything to be really ready for that fight."
Liverpool visit Southampton in the league later on Friday before City meet Brighton and Hove Albion in the FA Cup semi-finals on Saturday.
(Reporting by Hardik Vyas in Bengaluru; Editing by Amlan Chakraborty)
