They can destroy everything they want but we'll keep on fighting'.
In a crisis that has rattled stock markets and anxious a European Union that is already struggling with Brexit, Catalonia held a banned independence referendum on October 1, with Puigdemont threatening to declare a breakaway state based on its results.
Prime Minister Mariano Rajoy insists that Catalan leader Carles Puigdemont, who heads the wealthy northeastern region's government, has broken the law several times in pushing for independence, thus justifying the imposition of central government control.
Madrid enjoys constitutional powers to wrest back control of rebellious regions in one of the Western world's most decentralised nations, but it has never used them.
Autonomy is a hugely sensitive issue in Catalonia, which saw its powers taken away under Spain's military dictatorship.
Home to 7.5 million people, the region fiercely defends its own language and culture.
"The main goal of these measures is a return to legality because there can not be a part of a country where law is not applied, where law doesn't exist", he said on Friday in Brussels at the end of an EU summit in which European leaders including Germany's Angela Merkel and France's Emmanuel Macron had offered him their support.
Although the ruling Popular Party has enough majority to get the specific measures passed by the country's Senate, Rajoy has rallied the support of the opposition to give his government's actions more weight.
Speaking on Friday night at the Princess of Asturias Awards - Spain's answer to the Nobels - King Felipe described Catalonia as "an essential part of 21st century Spain".
The demonstration was originally called to protest against the detention of two influential separatist activists, Jordi Cuixart and Jordi Sanchez, who are being held on sedition charges accused of instigating protests in the run-up to Catalonia's banned independence referendum on October 1.
"Mariano Rajoy has announced a de facto coup d'etat with the goal of ousting a democratically elected government", he said, calling it "an authoritarian blow within a member of the European Union".
"Some are sowing discord by deliberately ignoring law", he said, adding pointedly: "All too often in the past the prospect of redrawing borders has been presented as a heavenly panacea that has resulted in a hellish mess".
It is also strongly rumoured the Nationalist coalition will vote for Catalonia to break away from Spain in Parliament next Friday, the same day that Madrid's measures are expected to be confirmed by the Senate.
Madrid this week cut its national growth forecast for next year from 2.6 percent to 2.3 percent, saying the standoff was creating uncertainty.