A former president, a world-famous Hollywood director and a rock music icon walk into a restaurant.

It sounds like the setup to a joke, but staff at Amar restaurant in Barcelona witnessed just that on Thursday night.

Employees were left in shock when 44th US president Barack Obama, director Steven Spielberg and musician Bruce Springsteen walked in unannounced.

Chef Rafa Zafra said Amar had been suggested by Spanish-American celebrity restaurateur José Andrés.

"They came recommended by José Andrés, who has a very close relationship with Obama," Mr Zafra told Spanish radio.

Mr Zafra said José Andrés told him that the booking was important. It was then that he realised that Mr Obama and his wife Michelle were in the city to attend a Springsteen concert, as was Spielberg.

Staff member Pol Perello uploaded a photo of them posing with wait staff and chefs to Instagram with the comment: "The pleasure this job brings you!"

"We gave them oysters, shellfish and fish from Roses, my classic - the caviar bikini - a little bit of everything... and super grateful!" Mr Zafra said.

Accompanied by security detail, the Obamas and Spielberg used Friday to visit some of Barcelona's most famous sights, such as the Sagrada Familia basilica and the Picasso museum. 

Springsteen's E Street band began their European leg of their tour on Friday at the city's Olympic Stadium.

The former president first met the rock legend on the presidential campaign trail in 2008. In 2021, they hosted the podcast Renegades: Born in the USA.