The English champions were beaten 1-0 at the Tottenham Hotspur Stadium last Tuesday, with Son Heung-min grabbing the only goal of the game for the hosts in the 79th minute.
City had been hot favourites heading into the tie, with many experts tipping them to win the competition for the first time in their history come May.
However, Spurs produced an energetic display to overrun Guardiola's side and they are now facing an early exit at the hands of a fellow Premier League club for the second season in a row.
Liverpool bested City at the same stage last year, but the Etihad boss has insisted that there will be no repeat of such an upset this time around.
"If you ask me what is going to happen, we'll be in the semi-finals; that is what I feel right now," Guardiola told Sky Sports.
"It's what I felt right after the game and when I reviewed the game. Maybe I'm wrong but what I feel now, we'll be in the semi-finals."
City are chasing the quadruple this year, after retaining the Carabao Cup in March, advancing to the final of the FA Cup and reaching the final five games of the Premier League season with the title still in their own hands.
On Friday Guardiola rebuffed Ilkay Gundogan's claims that City are "too nervous" in the Champions League, but he went on to admit that their route through the competition has not always been plain sailing.
"Football is a never-ending process; sometimes you step forwards, sometimes you step back," he added.
"Of course that competition [the Champions League] is more difficult, but the way we approached it, especially in that game, was good.
"We started not good against Lyon [lost 2-1 at home] and at the end, we qualified.
"I didn't expect to solve the problem in London. The result is not ideal but it's not a disaster. We are able to score goals and we are going to do it."