Casillas said to be a supporter of Mariano Rajoy's government (Reuters)

A barman that protected demonstrators form police has become a national hero in Spain, after a video of him driving back riot police went viral on YouTube.

Alberto Casillas, 49, prevented police from entering his café in Madrid, as dozen of anti-austerity protesters had looked for shelter from a charge inside the "Bar Prado", earlier this week.

A video posted online, shows Casillas standing in front of the bar entrance, holding his arms out to protect demonstrators telling police: "On my Life, you will not enter! It will be a massacre."

As police stood back, protesters started hugging and thanking Casillias.

"You, you really deserve credit", "it is you that represent us," some demonstrator told him.

Casillias soon became the symbol of the protests against Prime Minister Mariano Rajoy austerity budget plan that is designed to rescue Spanish finances.

People commenting on YouTube appealed for him to run as President and Casillias' Twitter account, opened shortly after the fact, was flooded by messages of gratitude.

However, interviewed by Spanish newspaper El Pais, Casillias revealed to be a supporter of Rajoy's government.

"Let me be clear. I am in favor of the Partido Popular. I am a supporter and voter of Rajoy, but on Wednesday it went too far," he said.

"There were excessive police forces. I am for compliance with the law, but above the law, there is humanity. I did what I had to do, that's all."

Casillas protests
Alberto Casillas, 49, prevented riot police to enter his café in Madrid (Twitter)