Guardiola says City did “the only thing I didn’t want” during the first half at the Stade Louis II on Wednesday, when they were forced back by the French side and conceded two early goals which eventually sealed their fate.
And while the Catalan admits his side have been caught out too often this season, he believes next season will bring progress, even if he refutes the idea that he will sell half of his current squad.
“People create a lot of expectation but we know that all the teams in that competition is so demanding,” he said at a press conference on Friday. “In England there has to be an awareness about that.
“A lot of the players were in the competition for the first time and we will learn. We will be stronger next season I think.
“We were close to qualifying. We scored six goals and of course we conceded six goals. When that happens it’s so complicated. Most of the goals were our mistakes.
“It’s happened many time this season and I think it is going to happen less next season. Hopefully we will learn.
"I don’t have too many regrets about how we competed except the first half, people can’t believe we weren’t there defending the result. It’s the only thing I didn’t want. But the opponent was good.”
Guardiola had tried to build on City’s impressive start to the season, when they won 10 games on the bounce, by introducing more complex systems designed to dominate games with one fewer defender and an extra midfielder, but was forced to abandon those plans in December following some damaging results, the most serious of which coming at Leicester City.
Since then he has routinely played a more traditional back four and City have won 13 of their 19 matches in all competitions, with the Blues in particularly fine form since Leroy Sane’s emergence in late January.
But the Blues have still endured some chastening results since Guardiola reigned in his tactical demands, most notably at Goodison Park and at Monaco in midweek, and that is what the Catalan knows he must improve if he is to make his team challengers in the Premier League and Champions League.
As many as 18 City players face uncertain futures at the club, though it is more likely that seven or eight could leave with five or six versatile replacements brought in.
And while Guardiola realises the need to freshen things up, he says it will be impossible to make wholesale changes and that, in any case, the base of the squad is already in place thanks to young players such as John Stones, Leroy Sane, Raheem Sterling and Gabriel Jesus.
“The people make a report about our performance in Monaco, and the people said we are going to change 12 or 13 players,” he said. “I am going to assure you it’s impossible today to do that. You have to be a little bit more responsible, you have to imagine being the club. Thirteen players have a contract and maybe you have to pay them to go there, to pay their salaries, and [then] pay £40m or £50m for every player, we are going to spend £500m or £600m, it’s impossible.
“We are going to try to improve the team, but do it in a way that’s possible in the market. Most of the players, the base is perfect, it’s done. John Stones next season will be a better player. The last month or month and a half John has made a huge step forward. Maybe it’s not the best John Stones you’ve ever seen but next season will be better, because he’s so young.
“It’s the first year players have come here to play in Europe, and people believe they are going to come here, put them on the pitch and they are going to play well. They need the process, they need time to build and to be settled, but I am delighted with his performance and how good he will be for your national team in the future, I am pretty sure of that, how important he will be. Of course he makes mistakes but it’s part of the process. I never saw a central defender or 20 or 21 years of age going into the last-16, quarter-finals or semi-finals or play in the big stages and not make mistakes, it’s impossible. We have to create a good environment for him to get him better, to help him. I’m talking about John Stones and all the other examples.”
Guardiola also insisted that some of his full-backs who are out of contract this summer - Pablo Zabaleta, Gael Clichy and Bacary Sagna - could yet stay at the club, and though he reiterated his message that he is happy with his squad as a whole, he admits there is a long way to go for both his defence and his attack.
He added: “It doesn’t mean all the full-backs will end their contracts and leave, some of them maybe are going to stay. We’re going to do what we’re going to do but knowing that a lot of players, I don’t know the average, they are going to stay here next season to help us because we believe in them because they did really well.
“I remember the performances against Barcelona here, the second half in Monaco, we are a team like we show all the season - that is not the Monaco game. We are not a team to be stable for 90 minutes. We are new in many many things.
“The way we want to play and a lot of players they are new playing in the Champions League. Sterling is the second year but the last year he played few times in the Champions League, so it is almost the first year. Sane is the first time playing on the biggest stages. People believed when we arrived that we came here we going to… that we were there.
“Of course we have to improve and be better in the competition for next season and be more stable. The chances we create, to score more goals and concede less chances and try to defend better. And of course in the boxes there is a big gap to improve for the next season.”