"The players are in good health and self-isolating at home. The Club has reported the cases to the relevant authorities", it said in a statement.
The three players join left-back Jordi Alba, centre-back Clement Lenglent and defender Dani Alves, who also tested positive this week.
Barcelona, currently seventh in La Liga, travel to Real Mallorca (15th) on Sunday.
Several Spanish clubs have reported Covid cases, such as Real Sociedad on Monday or Real Madrid in mid-December, but no match has yet been postponed.
According to La Liga and Spanish Football Federation rules, a match is suspended when a team does not have at least 13 players, of which five must be from the first team.
This puts Sunday's match between Atletico Madrid and Rayo Vallecano at risk because the latter team has up to 17 infected players, according to press reports, making it the hardest-hit squad in the first division.
Real Sociedad has reported 10 infected players, Cadiz has five and RCD Mallorca four.