The former Barcelona head coach has never gone beyond the last eight with Premier League side as he starts his fifth bid for the European trophy
With less than a year remaining on his contract, the City boss is starting what will be his final challenge for the European competition unless he signs a new extension.
But he has thus far failed to get beyond the quarter-finals, conceding heavily in exits to Monaco and Liverpool in 2017 and 2018, while City were dumped out by Tottenham in 2019 and were surprisingly beaten by French side Lyon last season.
“I have the feeling that we are close, every season when I analyse the way we went out,” he told a news conference ahead of the first game of this season’s Champions League campaign against Porto.
“I felt we are close but at the same time we make mistakes that make you feel we don’t deserve to go through.
“For clubs who are used to being in the latter stages it’s easier but having won the domestic titles the next [target for us] is the Champions League and we had a good opportunity.
“Now it’s a new opportunity and I believe. We talk about this and we have to do things differently. When you review the games; Liverpool, Tottenham, Lyon, I always had the feeling we were close, they were not better than us, none of them. There are little gaps but we have to solve them.
“When you don’t go through it’s because you don’t deserve it. And that’s all.”
Last season’s exit was particularly surprising when City were beaten by 3-1 by Lyon, who had finished seventh in Ligue 1. Guardiola has been accused of over-thinking tactics in the latter stages of Europe and said he took the responsibility for the last-eight defeat in August.
“It was a tough moment, I felt responsible for this,” he said. “How the club and players fought – I was not able to drive them on. I feel responsible watching the game, we were not good enough, we didn’t play bad.
“We had really good moments but made mistakes and in this competition you cannot do it.
“The reality is every team and manager has to dream with high expectations but the reality is we have not performed to the level.
“We have to accept it with humility, accept all the bad situations, improve and go through and accept a new challenge, start from zero again and try again knowing we have to improve, knowing the demands are so high.
“I feel so bad for the players but this is a new opportunity and we start again.”
The Champions League remains an important target for the club and City will start as one of the favourites again but Guardiola says they must first focus on getting out of a group that also includes Marseille and Olympiacos.
“Every season starts the same, you know the answers for many clubs it’s an incredible competition, it’s just the first game, then we play the second and see how far,” he said.
“We are far away from thinking about big targets, considering what’s happened [previously] we are not allowed to dream much higher.
“The reality is you try to win the first one and after that we’ll see how we can grow the team. We are still a bit away from where we want to be.”