The Crown is firmly attached to Constitution and to democracy, said Felipe VI again, recalling that its role is to preserve " unity and durability of Spain".
Led by losses for the two main Catalan banks, Spain's main stock market index lost nearly 3 percentage points in Wednesday's trading amid uncertainty over how the secession bid will proceed.
Videos have also emerged of the National Police crowding the lobby of the Pineda del Mar hotel and singing Spanish national songs, waving flags and calling for action to be taken against the protesters.
On Tuesday, huge crowds held street protests and unions staged a strike in Catalonia to protest the alleged police brutality.
European leaders have sided with Spain and, amid fears that Catalonia's secession bid could find echoes elsewhere on the continent, the EU has so far refused to step in.
It's anybody's guess what might happen if the prosperous northeastern region of Catalonia does actually try to secede. Asked about a Madrid intervention, he replied that it would be "a mistake that would change everything".
Catalonia says some 2.3 million people - less than half the region's electorate - voted in the referendum Sunday.
Catalan claims for independence date back centuries but have surged during recent years of economic crisis.
After considering timid and moderate the response of the European Union to the eve's events, Puigdemont recommended the bloc supports his initiative of worldwide mediation between the Generalitat and the administration of the also conservative Rajoy.
La Liga sides Barcelona, Espanyol and Girona have made a decision to join the general strike in Catalonia on Tuesday, Oct. 3.
Spain's National Court, meanwhile, said it will quiz two senior officers of Catalonia's regional police force and the leaders of two pro-Catalan independence civic groups who have been placed under investigation for sedition.
The court said the four will be questioned 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.
Millions of Catalans turned up to vote in the plebiscite, which was deemed illegal by the Spanish government and violence broke out, with local authorities reporting that almost 900 people had been wounded by riot police wielding batons and rubber bullets in an attempt to break up the voters.