The holders had to come from behind before romping to a 3-1 victory at home to Manchester United at Munich's Allianz Arena in Wednesday's quarter-final, second-leg to win the tie 4-2 on aggregate.
"We are in the semi-finals, so I'm very, very proud of my team," said Guardiola after goals by Mario Mandzukic, Thomas Muller and Arjen Robben cancelled out Patrice Evra's superb second-half strike for United. "I'm happy.
"My players have huge hearts. This is the best part of the season for me, now we're in a superior situation."
Having won 14 titles in four seasons as Barcelona coach, the 43-year-old Guardiola has already won three titles in less than ten months at Bayern after conquering the UEFA Super Cup, the FIFA Club World Cup and the Bundesliga with a record seven matches to spare.
"I often get asked which team I want but each side has their own qualities," he said. "Real have superior players with enormous qualities, such as [Cristiano] Ronaldo, Xabi Alonso, [Gareth] Bale etc. Atletico are pure passion and it's their first time in this situation. It's unbelievable for their fans what they have done so far.
"Chelsea have a lot of experience, with players like Petr Cech, [Branislav] Ivanovic, [Frank] Lampard and the Blues have a trainer with a lot of experience too. Each team have their own strengths and we'll analyse them as well as possible."
Having become the first German team to win the treble of Champions League, Bundesliga and DFB-Pokal crowns last season, Bayern are bidding to become the first side to defend former honour.
"I have been here nearly a year and I have seen why they won everything last year," said Guardiola, who has reached his 15th Champions League semi-final as a player or coach. "They have great team spirit and I am proud. It's an enormous honour to be here."