Bernardo struck the opener on Tuesday night as City won 2-1 thanks to Matheus Nunes' injury-time winner.
“I don’t forget Bernardo, what he has done for us this season,” said Guardiola.
“Now we are here he didn’t play as much but I don’t forget in November, December, January, February, March, when we didn’t win one single game and he was there every single time.
“Running 30km every single way, playing different positions and he didn’t stop running.
“It was a moment that was empty mentally. After that, not winning game, it was empty and tired.
“Bernardo played important games and he had an incredible, huge personality. He’s a player for me that is on another level."
"Kovacic was brilliant"
Guardiola also highlighted the contributions of Mateo Kovacic and Kevin de Bruyne.
He continued, “For many reasons. Today in the game we had Kovacic who was brilliant. All the players’ commitment. Maybe we miss a little quality.
“Kevin made an incredible assist for Macca and his control made a chip but he didn’t score.
“We didn’t create much, but it’s not easy against Aston Villa. They have low block five or six at the back.
“It’s not easy. It’s a question of being patient and today Kovacic and Bernardo helped us read that.”