"Mr. Torra must strongly condemn the violence, which he has not done so far," Sanchez said in a statement.
"The government of Spain reiterates that the problem of Catalonia is not independence, which will not occur because it is not legal and nor does the majority of Catalans want it, but rather coexistence," he said.
He added that Madrid has "always been open to dialogue in the framework of respect for the law," in an apparent reference to Catalan separatists' demands for another referendum viewed by the government as a nonstarter.
Torra has called on protesters to remain calm and be peaceful. He responded to the prime minister by saying that the government had "no proposal for Catalonia."
The peaceful protest turned violent when some masked youths blocked streets and lit fires as they hurled rocks and fireworks at police, who responded with tear gas and rubber bullets.
"The images of organized violence during the night in Barcelona have overshadowed the half a million people who demonstrated in a peaceful and civic manner to show they rejected the verdict," said Catalan interior chief Miquel Buch, who oversees the regional police.