The Toffees were furious when a hand-ball inside the penalty area from Rodri was not adjudged as a foul.
Even when VAR took a look at the incident, no penalty was given, which confused the home side and many watching supporters.
Guardiola thought the incident may have been waved away due to a possible offside, but states that if there was no offside, it should have been a penalty.
Pep said post-game: "The pass from Dele Alli to Richarlison looks like offside – but if it is not offside it's a penalty."
He added: "If one incident can have a whole impact on a season then I will review a lot of incidents my friend."