Guardiola, who was in charge of Barca for four years between 2008 and 2012, will succeed Jupp Heynckes as the Bavarian giants' coach in the summer.
"He will enjoy the tie," Xavi told reporters on Monday. "As the cule he is, he will want Barcelona to win, I imagine, even though he has a future at Bayern. As a big football fan, he will enjoy a semi-final like this a lot."
Bayern will host the first leg at the Allianz Arena in Munich on Tuesday.