Guardiola says Bielsa has been 'spectacular' to watch during his time in English football at Elland Road.
The pair have history, having met to discuss the game at length at Bielsa's home in Argentina when Guardiola was beginning to make his way in the coaching world, and Bielsa's arrival in the Premier League was described as a 'gift' by the Citizens' boss.
They played out an enthralling 1-1 draw at Elland Road last season and Bielsa then got the better of Guardiola, despite going down to 10 men in the first half at the Etihad, Stuart Dallas scoring twice in a famous 2-1 victory.
This season's first encounter however was a totally different story, Guardiola's men inflicting a damaging 7-0 defeat on Leeds.
Speaking a day after Bielsa's removal by the Leeds board, Guardiola said he felt for the Argentine, whose legacy would remain.
"I am so sorry for him," he said.
"His legacy is there in Leeds’ city and the club and I am pretty sure with the players. Unfortunately as managers we are subject to results and lately they were not good. But in the four seasons, he was spectacular to watch and I wish him all the best."
Bielsa is to be replaced by American Jesse Marsch. The former RB Salzburg and RB Leipzig man is expected to be unveiled imminently, ahead of 12 huge Premier League games in which he must steer the Whites to safety from relegation. On April 30 Marsch himself will come up against Guardiola, in an Elland Road meeting with title favourites Manchester City.