The Premier League struggled across all three European competitions last week, raising doubts about the quality of the English top-flight.
But Guardiola, ahead of meeting West Ham this weekend, insists: "Before, we were the best championship in the world, right? After what happened this week, that's not the case anymore.
"I am convinced that our championship is incredible. It's a fantastic championship, but in this competition where everything is decided in one or two matches, anything can happen. That means the other leagues are good too.
"Now everyone is talking about Bodo/Glimt in Norway, right?A high-level team. Victory against Sporting, victory against Inter Milan, victory against us, Atlético Madrid. Everyone is tough. Everyone is better prepared and has immense respect for each other."