Barcelona will join a strike called across Catalonia on Tuesday in protest at a violent crackdown by police of an independence referendum called by pro-separatist politicians for the region on Sunday.
In a TV address on Wednesday night, Puigdemont said: "This moment calls for mediation".
Catalan authorities "have placed themselves outside the law and democracy, they have tried to break the unity of Spain and national sovereignty", he said, according to a translation by the Financial Times.
Before the vote, polls indicated that a minority of around 40 percent of the region's total 7.5 million Catalans supported independence, but many opposed to the referendum did not participate.More news: Senate Intel Heads Say Trump-Russia Collusion Still an Open Question
Images of police using rubber bullets and batons on voters were broadcast worldwide over the weekend - prompting condemnation internationally and intensifying the anger that brought Catalans to the streets.
The court said the four will be questioned on Friday about their roles in demonstrations September 20-21 in Barcelona when Spanish police arrested several Catalan government officials and raided offices in a crackdown on preparations for the referendum.
Pique, part of Spain's World Cup-winning squad in 2010, also added that he would retire from global football if his stance on the matter was regarded a problem.
About 80% of Catalonians voted to separate from Spain in a separate independence referendum in 2014, but that was non-binding.More news: Google Launches Home Max and Home Mini Smart Speakers
"I want to highlight (to all of the citizens of Catalonia) that we live in a democratic state where anyone can defend their ideas, within their respect for the law".
Carles Puigdemont, the region's elected leader, has asked for European Union mediation in negotiations and said Catalonia has "won the right to an independent state".
Spain's King Felipe delivers a speech at the Palace of Westminster in London, Britain July 12, 2017. He has indicated that Catalonia could declare independence next week.
Bartomeu confirmed two directors, vice-president Carles Vilarrubi and Jordi Mones, had resigned following an extraordinary general meeting on Monday.More news: Yahoo Triples Likely Scope of '13 Hack to 3 Billion Users
The region's leaders defied Madrid by holding a banned referendum on independence on Sunday.
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