City beat Bayern 3-0 in the first leg and are in the driving seat for a semi-final spot, with six-time European champions Bayern in turmoil after their German Cup exit two weeks ago, first-leg loss and draw in the Bundesliga on Saturday.
"We come here to play one football game, 11 men against 11 men, to try to do better than our opponent in this game," Guardiola told a news conference on Tuesday.
"We cannot play, competing against history. For us, it is a new opportunity to prove ourselves against one of the best in Europe. Tomorrow we don't play against history, we don't play against what they have achieved," he said.
Guardiola warned that Bayern, despite any internal turbulence, would go out believing they could turn the tie around.
Bayern's Sadio Mane was dropped and fined after clashing with teammate Leroy Sane following their first-leg defeat.
City are still looking for their first Champions League trophy having reached the final once, in 2021.
"I know the mentality of this club (Bayern). It is everywhere. It is in the skin and I know they believe they can do it. We believe too," Guardiola, who coached Bayern from 2013-16, said.
"When you are in this type of club, with the history they have in the past in this competition, it is what it is."
Guardiola's City side, who are unbeaten in 14 matches in all competitions, are looking to peak at the right time this season.
They trail leaders Arsenal by three points in the Premier League title race and play Sheffield United in the FA Cup semi-finals on Saturday.
One of the keys to Guardiola's success has been striker Erling Haaland, who scored twice in their weekend 3-1 home victory over Leicester City, increasing his goal haul to an impressive 47 across all competitions this season.
Guardiola will also have midfielder Phil Foden back after injury, though the midfielder is not expected to start.
"Definitely it is good news for us," the Spaniard said. "He has only one training session yesterday but he travelled with us and will be on the bench."
Asked how long Foden could play for Guariolas added: "90 minutes for sure no. But he is a special player who does not need a lot of training sessions to be fit. It is important not just for tomorrow."
