The Reds remains level on points with Chelsea and City at the top of the Premier League table ahead of the international break, after a gruelling run of matches.
Klopp's men have faced seven fixtures in 23 days that included encounters with City, Paris Saint-Germain, Tottenham, Chelsea and Napoli.
"And we hope that they come back healthy and play these easy competitions, the Premier League, the Champions League and all this.
"It's tough times for the boys, eh? But I said already in an interview, we have to start thinking about the players.
"Somebody asked me: 'Is the level of the game because of the intensity?' Already in the question, there is criticism; it could have been better if you were fresher.
"If you want to see fresher, give them a summer break -- for Jordan Henderson, it was exactly two weeks, which is funny," the German added.
"But that's how it is. That's why I say, going away is not a big problem, but now you call a manager of any country and ask him to leave out one or two players and he says: 'I am under pressure as well,' because now it's Nations Cup.
"I don't exactly know what you can win, but there is some final next summer or something so ... that's it."