A run of three defeats in four Premier League matches has seen Guardiola's side slip from first to third in the Premier League table, severely damaging their chances of retaining the title they won with a record 100 points in May.
City follow up Sunday's visit to Southampton with a home match against leaders Liverpool on Thursday, before struggling Championship side Rotherham United visit in the FA Cup three days after that.
Liverpool are 10 points clear of City after crushing Arsenal 5-1 on Saturday.
Guardiola said that even if City lost all three of their next matches, he would not waver from the high-pressing, fast-passing principles with which he has made his reputation as a coach.
"That is not going to happen. It did not happen in the first year; it is not going to happen," he said.
"Why should I? Because I lost two games? No way. It is definitely not going to happen.
"The same applied in my first season when I answered this question, 10 or 20 times, when people wondered about this guy, about what he believes, coming here and playing this way in England.
"It's not because I ever tried to show you through my words that I am special, or better, or unique, or something like that. I defend what I believe, and I believe in that."
City's unbeaten start to the Premier League season was ended by a 2-0 defeat at Chelsea on December 8, but they appeared to have rediscovered their form as they beat Hoffenheim in the Champions League.
They then defeated Everton in the Premier League before beating Leicester City on penalties to reach the semifinals of the League Cup, keeping alive the possibility of a clean sweep of four trophies this season, a feat unprecedented in English football.
Successive defeats against Crystal Palace and Leicester in the league were significant setbacks, with Guardiola suggesting that he and his players had to work harder to tackle the strengths of their opponents.
"Every team has its specific things," Guardiola said. "(At Leicester, goalkeeper Kasper) Schmeichel put long balls there and there, and Southampton are always (playing) in the middle. We try to discover what they do.
"But change? That is not going to happen, because I trust what we do. I trust a lot in the way we want to play.
"You can lose two, and three, and four, five. That can happen. Tomorrow we can lose, then again at Liverpool and again in the FA Cup.
"In my experience, when this happens is for everyone to look in the mirror, and work harder, harder. After that, you win one or two, everyone is coming back, and everything becomes normal."
Guardiola said he had spent plenty of time reflecting on his own performance as manager during their recent run.
"I'm disappointed in myself," he said. "I look at myself first of all. What can I do to help the players?
"It is the job of a manager to analyse through the game. You look for what you have to do better."
Guardiola, though, refused to get too despondent, pointing out that City's performance over the first half of the season has largely been positive.
"We got 44 points in the first half of the season. If you get the same number of points in the second half, that's 88 points.
"With 88 points, you are champions. At least, you have the numbers to be champions. Most of the Premier League champions in the past 20 years won it with fewer points."
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