The EU’s executive has called for the Spanish and Catalan governments to begin talks to resolve the regional independence crisis that has escalated since Sunday’s referendum, but said Madrid had the right to use “proportionate force” to uphold the law.

More than 900 people were injured after Spanish police attempted to halt the vote by raiding polling stations, beating would-be voters and firing rubber bullets at crowds.

Addressing the European parliament in Strasbourg on Wednesday, Frans Timmermans, the vice-president of the European commission, said the images emerging from Catalonia were saddening, but it was clear that the regional government had “chosen to ignore the law” when organising the referendum.

“Let me be clear: violence does not solve anything in politics. It is never the answer, never a solution. It can never be used as a weapon or instrument,” he said. “Europe knows this better than anywhere else … It is a duty of any government to uphold the rule of law and this does sometimes require proportionate use of force.”

Timmermans said it was “time to talk” and backed the Spanish prime minister, Mariano Rajoy, to bring the dispute to a peaceful resolution. He said the European commission president, Jean-Claude Juncker, was in touch with Rajoy but stressed that the vote on Sunday was “not legal” and it was “an internal matter”.

The Catalan president, Carles Puigdemont, and other senior Catalan politicians, including the mayor of Barcelona, Ada Colau, have called repeatedly for the EU to weigh in on the issue.

“The European commission must encourage international mediation,” Puigdemont said on Monday. “It cannot look the other way any longer.”

Writing in the Guardian last week, Colau made a similar plea. “The European Union came about as a project to safeguard and guarantee our rights and freedoms,” she said. “Defending the fundamental rights of Catalan citizens against a wave of repression from the Spanish state is also the same as defending the rights of Spanish and European citizens.”

Despite the Spanish authorities’ attempts to stop the referendum, which both the government and the country’s constitutional court had declared illegal, 2.26 million Catalans took part. A Catalan government spokesman said 90% of participants had voted for the region to become independent. The region has 5.3 million registered voters.

On Tuesday night, King Felipe accused the Catalan authorities of attempting to break “the unity of Spain” and said their push for independence could put at risk the country’s social and economic stability.

In a rare and strongly worded television address, he described the regional government’s actions as “an unacceptable attempt” to take over Catalan institutions, adding that it had placed itself outside both democracy and the law.

Puigdemont has said Catalonia will act to declare independence at the end of this week or early next week. He warned the Spanish government that any move to stop the independence process by using article 155 of the constitution to take control of the region could be the “ultimate mistake”.

On Wednesday, Colau called for dialogue instead of threats. “Neither a unilateral declaration of independence nor 155,” she tweeted. “We need dialogue and bridges more than ever. Mediation and a jointly agreed referendum.”

On Tuesday, thousands of people took to the streets of Barcelona to protest against the actions of some Spanish Guardia Civil and national police officers during the referendum.

Amnesty International said it had documented a “dangerous and disproportionate” use of police riot equipment on Sunday. “In several cases, the actions of national police and civil guard officers involved excessive and unnecessary use of force and the dangerous use of riot control equipment, injuring hundreds of peaceful protesters,” said John Dalhuisen, the group’s Europe and central Asia director.