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City had five players booked and were awarded a controversial penalty while Porto defender Pepe was lucky to avoid a red card for thrusting his knee into Raheem Sterling's chest in an off-the-ball incident.
Conceicao accused Guardiola of using "ugly words" but the City boss insisted he behaved in a proper manner.
"We didn't want itto be unpleasant. He believes we are,maybe he's right," Guardiola told a news conference ahead of Saturday's Premier League clash with West Ham.
"I don't think so. Honestly, I don't think so. I'm pleased with how we behaved from minute one to minute 90. But if he believes this, okay, maybe he's right. We will see."
Porto only have to wait five weeks for the return fixture when City travel to Portugal for matchday five.
Meanwhile, Guardiola has again defended Sergio Aguero after a number of football pundits criticised the striker for touching assistant referee Sian Massey-Ellis.
Former players Alan Shearer and Ian Wright were among thoseto speak out onthe incident in the 1-0 victory over Arsenal after the Argentinianwas unhappy about a throw-in being awarded to the Gunners.
Aguero grabbed Massey-Ellis at the top of theshoulder close to her neck before she brushed him away.
Guardiola defended his player and said there was no malice in his action despite the criticism.
"All the people looking from outside judge, I know the intention from Sergio," he said.
"Sergio put his hands in a normal way like he does many times to me, on or off the pitch or when I hug him, when there is a substitution or when sometimes he touches the referee as well or an opponent.
"If I’d seen some aggression, maybe. I think it was normal as I know him perfectly.
"He’s been a huge star in the world but he’s humble, the nicest people I've met.
"What is important is his intention and his intention was normal, to talk to her in a normal way, it was not a bad word, it was just normal.