Guehi was not eligible to feature as City secured a 5-1 aggregate win over Newcastle in Wednesday’s semi-final second leg and is also set to be unavailable for the final against the Gunners at Wembley on 22 March.
City completed the signing of the 25-year-old England centre-back from Crystal Palace after their 2-0 victory in the first leg against the Magpies.
However, competition rules state that a player must have joined the club “before the close of the Winter transfer window, or the first leg of the semi-final (whichever is earlier)” in order to be eligible to take part.
“Hopefully we can persuade the Carabao Cup that Marc [Guehi] can play in the final. I don’t understand why he is not allowed to play,” Guardiola said.
“You sign a player for a lot of money and then he cannot play because of a rule I don’t understand. Hopefully they can change it,” he added.
City’s other January arrival, winger Antoine Semenyo, joined the club from Bournemouth four days before the first leg away to Newcastle and was able to feature — even scoring in that match.
“Antoine arrived before the first game so he could play. Now it’s the final. Why shouldn’t Marc play? Why not? We pay his salary, he is our player,” Guardiola continued.
“I told the club they must ask, definitely. I don’t see the reason why he cannot play in the final in March, when I have been here for many years.
“The rules about signing players come from Fifa, Uefa and the Premier League, who say when the transfer window is open, if you sign a player he should be able to play, no? It’s logical. Of course we are going to try to ask for him to play. Pure logic.”
When asked what response he expects from the EFL, the City boss replied: “No. But we will try.”
City have already benefited from a rule adjustment this season that allows players to represent two different clubs in the same competition rather than being cup-tied.
This change enabled Semenyo and Max Alleyne to appear in the semi-final ties, despite having previously played for Bournemouth and Watford respectively in earlier rounds.
