An end-to-end first half saw Erling Haaland tap home to give his side the lead before the linesman flagged for offside.
No one could have any complaints about that decision, but Enzo's heavy tackle on Bernardo Silva shortly after could have easily resulted in a red card.
Instead, Darren England brandished a yellow, and Guardiola felt the Argentine should have been sent off for his overzealous challenge.
"Chelsea midfielder Enzo Fernandez celebrated that heavy tackle on Bernardo Silva as he thought it was so clean but ends up booked by referee Darren England. He got the ball but also the man," BBC Sport's Nizaar Kinsella wrote.
"Man City's bench, including manager Pep Guardiola, were calling for a red card."
Enzo was arguably lucky to still be on the pitch for making that tackle in this day and age, but it does show the 25-year-old's passion for the cause and eagerness to win.