The Spanish forward found himself omitted from the first eleven for the fourth game running as Guardiola plumped for the attacking triumvirate of Lionel Messi, Alexis Sanchez and Isaac Cuenca.
Although the former Valencia hitman came off the bench to grab Barca's fourth goal, Guardiola had to fend off questions from journalists over Villa's prolonged bench duty role.
"When I tell you that I have a lot of trust and faith in Villa, I mean it," Guardiola told a post-match conference.
"Thiago did not start either and he has been playing at a very high level, and neither did Andres [Iniesta]. I cannot justify every time he has been a substitute. Not everyone can play, but I trust everyone. I know every player and what they can bring to the fare."
Guardiola also hailed the character of Messi, who soldiered on after suffering a challenge during the game.
"Messi does not complain, nor does he fall to the ground, if he does not feel pain," Guardiola gushed, after the Argentine was seen grimacing in pain during the match.
"I was worried, but he said he was fine so I decided that he should continue. He gives us many things as he can unbalance the game."
Further goals from Gerard Pique and Carles Puyol ensured the Nou Camp outfit stayed within touching distance of arch rivals Real Madrid on 28 points, three behind Jose Mourinho's charges.