The identity of those involved have not yet been confirmed by police, who said their investigation is continuing.
The police operation was conducted on Monday after an investigation into financial issues at Barcelona.
Those issues are thought to be related to the ‘Barcagate’ scandal in 2020 when the club denied hiring a firm to attack their own players on social media.
The club’s presidential elections take place on Sunday after their previous president, Josep Maria Bartomeu, announced his resignation in October.
According to Spanish media reports, Bartomeu is among those arrested – although police have not confirmed this.
In a statement, Barcelona said
The police searches related to the contacting of monitoring services on social networks.
FC Barcelona have offered up their full collaboration to the legal and police authorities to help make clear facts which are subject to investigation, the club said.
The information and documentation requested by the judicial police force relate strictly to the facts relative to this case.
FC Barcelona expresses its utmost respect for the judicial process in place and for the principle of presumed innocence for the people affected within the remit of this investigation.
Police said they also searched four other properties as part of their investigation, which has been going on for almost a year.