Ahead of this week's Champions League return game, Guardiola was asked about Conceicao's criticism of his antics on the touchline during Porto's earlier defeat.
"I'm not in agreement. He can say his opinion but I'm not agreeing that we pressured the referees," said Guardiola.
"The history speaks for itself. We are not the team to do this. I would admit it. When the action happens that you don't agree you can talk to the assistant. The five years in Spain and Germany we haven't done this. I don't agree."
He continued: "It will be a tough, physical game for sure. They have an incredible team spirit, they fight for eachother. It will be tough. It's normal, Champions League away, we know it. They are one of the top teams in Portugual, same with Olympiacos they have to win every weekend. When you have this mentality this makes them so dangerous. We expect, like I expected when they came here, it will be a difficult game. It will be."