0913 GMT July 21, 2019
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, BBC wrote.
"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 its Portuguese visitor.
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 its first four goals inside 28 minutes and its fifth in the 40th minute, and even prolific goal-scorer Lewandowski was surprised at the half-time score line.
"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."