Cereceda, whose club Colo Colo were notified on Friday by the South American Football Confederation of the positive result of a test taken on Aug. 17, opened the scoring with a penalty in Chile's 2-0 win away to United Arab Emirates.
"What I generally recommend to myself is that with anyone going through a moment of weakness, you have to double the closeness, the affection and the company," Bielsa told a news conference in Abu Dhabi.
"Today I was told a very illustrative phrase, something like there are no saints without a past and no sinners without a future. As I adhere to that principle, I'm right at Roberto's side."
Cereceda scored in the fifth minute and midfielder Pedro Morales added another goal in the 37th of the match in Abu Dhabi.
Chile played the last 13 minutes a man short after defender Sebastian Toro came off with a head wound and there were no more substitutes available in a small squad.
Bielsa sent four players home on Thursday after their club Universidad de Chile criticised their call up despite the fact that one of the conditions for renewing his contract after the World Cup was complete autonomy on player selection.
Cereceda's doping test was taken after a match in the Copa Sudamericana, South America's equivalent of the Europa League.
Chile play Oman in Muscat on Tuesday.
