This comes amid an escalating crisis over the region’s push for independence.
The Spanish Prime Minister said he wanted to dismiss Catalan leader Carles Puigdemont, his vice-president and all regional ministers.
Rajoy’s speech was met with applause in the Spanish senate, where his Partido Popular has a majority.
With no sign in sight for an end to the Catalan crisis, the two leaders of the Greens in Parliament, Ska Keller and Philippe Lamberts, have now urged the European institutions to offer mediation.
The MEPs also called on both the Spanish and the Catalan government to “come back to dialogue.”
German MEP Keller said, “The coming days will be absolutely decisive. The actions of EU leaders and the Spanish but also Catalan governments will determine if we face dangerous escalation or will have one last chance to establish dialogue and find a peaceful solution.
“Rather than backing one side or the other, as President Tajani did, the European institutions need to urge both parties to talk. They need to offer mediation to facilitate the dialogue. It’s a shame that EU leaders didn’t discuss it at the summit last week.”
Her colleague Lamberts, a deputy from Belgium, said, “It would be foolish to dismiss this as an internal Spanish problem. Presidents Juncker and Tajani might want to ignore this crisis in an effort to protect their EPP colleague Rajoy. But if they don’t act now, this political, social and economic crisis will only escalate further, leaving the EU to deal with a much bigger problem.
“This is a time for calm heads. The Spanish government must refrain from suspending Catalan autonomy. In turn, the Catalan Parliament needs to refrain from declaring unilateral independence and should attend the senate session in Madrid to open the possibility for dialogue.”
Lamberts added, “To get out of the crisis both sides need to give up their prerogatives.”
Another MEP, Richard Corbett, has accused the Spanish government of being “heavy handed” in its approach to the current crisis.
The S&D group member said that while the referendum was illegally organised, “the central government could have simply ignored it.”
He added, “No other country is likely to recognise Catalonia as an independent state simply on this basis, so there was no need for the central Spanish government to be so heavy-handed.”
He said, “At present the EU is in a protracted process of dialogue with the Polish and Hungarian governments about laws that appear to put in question basic principles of the rule of law. Member states (reluctantly) accept that the European Commission has a right to raise questions about such national legislation.
“They haven’t given it powers to intervene on individual policing operations, and would be reluctant to do so. But they can’t stop debates in the European Parliament and the platform it offers to parties across the political spectrum and from all member countries to raise issues and to criticise governments.
In his speech on Friday, Rajoy said he was calling for exceptional measures because there was no other choice and said “law, democracy and stability” needed to be returned to Catalonia.
He accused the Catalan government of dividing families and fracturing society. Many people had already suffered too much, he said, and the uncertainty was driving businesses out of the region
Article 155 of the Spanish constitution empowers the government to take “all measures necessary to compel” a region in case of a crisis.
It would enable Madrid to take control of Catalonia's finances, police and public media.
On Thursday the Catalan Parliament began discussions over a possible declaration of independence.
It came after Catalan leader Carles Puigdemont failed to reveal a favoured course of action, and called on MPs to decide on a response.
The Catalan government said that of the 43 per cent who took part in the referendum, 90 per cent were in favour of independence, but the Constitutional Court ruled the vote was illegal.