The Germans overturned a 3-1 first-leg deficit against Porto, winning 6-1 to advance 7-4 on aggregate.
Guardiola's side scored five goals in a thrilling first half at Allianz Arena.
"I know how very important it was," the 44-year-old ex-Barcelona boss told ZDF Television. "It is about winning just like at Barcelona."
He added: "It's easy to love my players now. I am the coach of extraordinary players. I didn't expect such a first half.
"We can still play better. We lost the ball here and there and we can improve on that. We had a few problems in the second half. They had only a few chances in the second half but you should never relax in the Champions League."
Speaking before the game, Guardiola admitted the expectation at the Bundesliga club was to win the Champions League, and not just settle for domestic league and cup glory.
Striker Robert Lewandowski scored two and Thiago Alcantara, Jerome Boateng, Thomas Muller and Xabi Alonso also netted as Bayern dominated their Portuguese visitors.
Porto barely troubled Bayern in the first half, and Guardiola added: "We played a different game. We knew Porto better after the first game.
"Now we have to fight otherwise we will not achieve what we set out to do."
Bayern scored their first four goals inside 28 minutes and their fifth in the 40th minute, and even prolific goal-scorer Lewandowski was surprised at the half-time scoreline.
"Many people thought we couldn't do it, but we are FC Bayern Munich," said Lewandowski. "We knew we had to step on the gas, but to go five goals up at half-time is really crazy."
Germany striker Thomas Muller added: "It couldn't have gone better. Sometimes it's fun to play with your backs against the wall. We all had hopes, but no-one expected that."
BBC Radio 5 live's Pat Nevin at the Allianz Arena: "Bayern were ruthlessly efficient in the first half. They were brilliant, scored great goals against a poor team.
"But they made some tactical changes and looked bordering on anaemic in the second half. They didn't look up for it. They could have been pulled back in the end but there's more to come from this team.
"The Champions League got predictable a long time ago. It's a little bit of a shame. We try not to be biased during commentary but Porto were the last of the little teams and they've been absolutely whacked, swatted like flies out of the way.
"There's always Spanish and German teams in the semi-finals, the odd time an Italian or English team but that's it. And even then it's the same teams. But it doesn't mean it's not exciting."
Porto coach Julen Lopetegui accepted his side were beaten in a disastrous opening spell.
"We are very disappointed because we had a lot of expectations," he said. "But it just turned bad very early on and it became difficult for us to play our game against such a good team. We lost the game in those 20 minutes in the first half.
"We tried to change things in the second half and I think we improved a bit but it was too late.
"We are sad, but we made a great campaign in this Champions League. In 11 matches this was our only defeat.
"Bayern is one of the best teams in the world and the favourite to win the title."
Bayern boss Guardiola ripped his trousers during the game. Story and pictures here.
Bayern Munich's progress to the semi-finals of the Champions League was "about life or death", according to manager Pep Guardiola.