Guardiola finally ended Manchester City’s long wait for European glory when he guided the club to success in the competition last season.
It had been City’s 12th successive campaign in the Champions League and their seventh under Guardiola, who had previously won it twice as Barcelona boss.
City will look to cement their place in the quarter-finals of this year’s competition on Wednesday when they go into the second leg of their last-16 tie against FC Copenhagen holding a 3-1 aggregate lead.
City manager Guardiola said: “It’s getting better and tougher. Always I had the feeling, when I arrived in Barcelona in the first years that OK, we arrive in semi-finals.
“Now to reach the semi-finals is so difficult. The teams are better, managers are better.
“Everything is even more difficult than when I was a football player.
“But at the end, the better teams always go through. When you play two good games, you have more chance to go through.”
Guardiola insisted, however, his triumphs with City were no more special than those he achieved with a Lionel Messi-inspired Barca side in 2011 and 2013.
He said: “I would not say that. Otherwise we would undermine what we achieved in Barcelona and I would not like that.
“Every moment is every moment. Every title you win is difficult. It’s not taken for granted.”
City outplayed Copenhagen in the first leg at the Parken Stadium three weeks ago and could have won more comfortably than the scoreline suggests.
Yet Guardiola maintains the tie is not over and will not allow focus to switch to Sunday’s crunch Premier League showdown with title rivals Liverpool yet.
He said: “Selection will depend on how people recover from the last game and that’s all.
“In this competition it is so really important to be focused because in football everything can happen and you have to be aware of that.”