The Foxes were frustrated throughout against Jamie Vardy's former side, who made it tough for City and hit the post in the closing stages as they ensured a replay at King Power Stadium on Tuesday week.
Puel made eight changes to his side for the game on the back of a hectic festive fixture schedule – including the returning Harvey Barnes in midfield – but he felt that his team didn't do enough to win the game on the day.
He said: “Congratulations to Fleetwood because they played very well with quality. It was a special game, a cup game and it had a good atmosphere. It had all the ingredients to make an upset, with the pitch making it difficult to play on the floor.
“We knew before the game it would be tough against a good team. The atmosphere, the stadium and the pitch are not the same as in the Premier League. It was a tough game to play.
“I picked a team that can win the game, knowing the fitness levels of my players after four games in 10 days. I think there is no excuse about this. We have had a good team on the pitch but it was not enough from the play.
“I think it was a disappointment in the first half because we didn't find the space to play with quality and create chances to score. After that they began to believe that is possible to win this game.
“The second half there was duels, battles, long balls and set plays and sometimes it is a lottery. We needed more control of the game. They believed until the end they could create an upset from a set piece.
“It was good to give some game time also to young players like Harvey Barnes, but of course it was a minimum from us today to make the replay.
“They are a good team and it is a good thing to have the possibility to play the replay at home, and to give some game time to players like Adrien Silva and Matty James after their comeback."