Activists Jordi Sanchez and Jordi Cuixart have already been sent to prison, after October’s referendum was deemed illegal by Spain’s government.
They are being investigated for alleged ‘rebellion’.
Guardiola is a known supporter of the campaign for Catalonia to become an independent state and he attended a pro-independence rally in Barcelona in the summer with the president of the Catalan government, Carles Puigdemont, along with tens of thousands of demonstrators.
He told the mass crowd that he would be voting for independence on October 1 “even if the Spanish state doesn’t want it”.
Although the vote was not recognised by Madrid, Spanish police have launched investigations into high-profile figures who attempted to influence public opinion.