"The attitude of Mr. Guardiola during the game was not very pleasant and it wasn't of the [City] bench either," Conceicao said after the game.
"Besides the way in which he spoke to my players and the referees. He spoke about our country [Portugal] and they weren't nice words so I had to respond, because he who doesn't feel that [comments] is not the son a good person."
Conceicao also told the club's website: "I have to learn from him, in the way he conditions the referees, how he talks to the rival players and the [rival] bench. I have to learn a lot in that respect."
Porto felt their team were on the receiving end of some wrong decisions by the officials and the club's headline of their match report read: "A Lithuanian and a Dutch [in reference to the Wednesday's officials] helped the English party."
Conceicao also believed City were given a helping hand and apologised for his previous criticism of referees in the Portuguese league.
"The referee had a tremendous impact on the match," Conceicao said. "[Agustin] Marchesin is bruised on his leg right now, because of the foul on him.
"That allowed them to draw, and it raised their confidence, as they were finding no way to breach our defensive line. And when they did, they posed no danger. Just before the break, we had one or two more opportunities to score, as we reached their goal with danger, always remaining humble and skilled in our defensive organisation, and then Pepe is pushed from the back on a throw-in.
"That should have been a penalty and a chance to go into the break with the lead. Then came the free-kick for the 2-1, which wasn't a foul in my opinion. There were situations where nothing was called, others when too much was called.
"I feel I owe an apology to Portuguese referees. Looking at the refereeing team and the VAR tonight, these international referees have a lot to learn from the Portuguese City of Football."