The UN High Commissioner for Human Rights, Zeid Ra'ad Al-Hussein, said he was "very disturbed" by the violence in Catalonia.
Madrid's top official in Catalonia said he lamented the violence but blamed the regional separatist government for "exposing citizens to danger".
Mr Puigdemont must return to the path of law before any negotiation could take place, it said said in a statement (in Spanish). "When I see a country where we have known how to coexist and set a good example to follow around the world", he added, leaving the final part of his sentence to drift, unfinished.
"It is the responsibility of the legitimate state powers to ensure constitutional order", Felipe said. Almost 900 people were injured, the BBC reported.
"We are to declare independence 48 hours after all the official results are counted", said Catalan leader Carles Puigdemont in an interview with the BBC Tuesday. "We must stop the violence and confrontations", he said.
People watching in a bar in Barcelona whistled and booed after the king's speech.
There was uncertainty about whether Mr. Puigdemont would unilaterally declare Catalonia's independence, a move that would raise tensions even further.
Spain's prime minister Mariano Rajoy indicated that he will discuss the issues with all of the parliamentary political parties and talks are also planned with European Commission president Jean-Claude Juncker.
The commission, the executive arm of the 28-nation European Union, said in a Twitter message that "these are times for unity and stability, not divisiveness and fragmentation". But now I am more for independence than anyone, thanks to people like that.
A pro-independence protest after Sunday's referendum. "They [European officials] have never wanted to listen to us".
Catholic leaders voiced pleas for peace after a Catalonian regional referendum vote on secession from Spain drew a strong police reaction.