The reigning European and world champions currently hold a two-goal advantage over their Danish counterparts after they claimed a 3-1 first-leg victory at Parken Stadium three weeks ago.
Man City have not lost any of their previous five meetings with Copenhagen, winning their last home encounter 5-0 in October 2022, but Guardiola has insisted that "everything can happen" in football and his side must "respect" Wednesday's opposition.
"In football everything can happen, and we have to be aware of that," Guardiola said at a press conference on Tuesday. "We have respect for Copenhagen and how they play.
"The Champions League is Champions League. The best eight teams in Europe [will move to the next round]. We have the chance to be in quarter-finals again and this is the target. We're not far off that.
"The way Copenhagen defend - they are compact - and all the movements they do really well. I am always aware of the opponents, but I especially look at our players.
"We struggled there last season; Bayern Munich were not able to win in Copenhagen (during the group stage).
"They play two years in a row with the same manager (Jacob Neestrup), and they have a strong striker. They are compact and do really good movements."
"My concern is always there," Guardiola added. "Otherwise I would not be here, but I prefer to start 3-1 up rather than 0-1 down.
"I would like us to be ahead 7-0, but that normally doesn't happen in the Champions League. I want us to perform the way we have to do.
"Red cards or bad decisions can happen in football. If we conceded another goal in the group stages, we are second in the table and the draw would have been Real Madrid not Copenhagen.
"In football the details make the difference. Prepare well, mentally and read what they have to do. Respect Copenhagen, because this competition deserves it."
Guardiola believes the Champions League has become stronger in recent years, adding: "The competition is getting better, tougher. Always I have the feeling to arrive in the semi-finals is harder.
"Teams are better, managers are better. More difficult now than when I was a player. But at the end the better teams always go through."
Meanwhile, the Catalan boss has confirmed that Jack Grealish is "not ready" to return from a groin injury and was unable to put a timeframe on his potential comeback.
Man City are looking to extend their unbeaten run in all competitions to 20 games when they face Copenhagen, who suffered a 2-0 away defeat to Midtjylland in the Danish Superliga last Friday.