The Belgian midfielder limped off in the bruising midweek Champions League draw with Atletico Madrid and required stiches in his foot, but was still named amongst the substitutes at Wembley.
Guardiola says De Bruyne, who spent time warming up in the second half, felt fit enough to play against Jurgen Klopp’s men, but the boss decided against introducing him off the bench to avoid aggravating the playmaker’s injury further.
“He still had four stitches in his right foot when he hit the ball,” Guardiola explained at his post-match press conference.
“He could walk and run, but the ball was disturbing him and at the end if he plays and opens up two or three stitches maybe we lose him more.
“Of course, Kevin was happy in the condition and could play maybe from the beginning because he feels fit, maybe to play in the second half, but I didn’t want to take the risk to lose him, in case it opened up the injury again or got an infection.
“That’s why I took that decision. When you play a lot of games and tough ones, these situations can happen.”
Liverpool’s dominant first half display meant City were forced to chase the game at Wembley.
The Reds raced into a three-goal lead in the opening 45 minutes, with Sadio Mane netting a brace after Ibrahima Konate headed in the opener.
Jack Grealish pulled one back immediately after the restart and Bernardo Silva scored in added time to give City hope, but Liverpool held on.
Guardiola made just one substitution in his bid to get back into the game, with Riyad Mahrez replacing Gabriel Jesus after 83 minutes.
The Catalan felt many of his starting XI were playing well, but acknowledged injuries played a part in his decision not to make more changes, with only Mahrez and Rodrigo free of fitness concerns.
“Kevin could not play, Kyle could not play, but it is what it is with the season we have,” he added.
“We have the situation, but it is what it is. We play a lot of games and we don’t have the biggest squad.
“When everyone’s fit it’s okay, but if there’s a few injuries it’s not enough.
“Riyad was fit, Rodri [too]. The other ones there were problems.
“Fernandinho played amazing, Bernardo and Joao and I think Gabriel was playing good and Raheem was playing good, that’s why sometimes you don’t do it.
“Of course, had we scored the third goal, I’m pretty sure in extra time we could do it, but in this moment we didn’t have many options.”
