"In culture we build bridges, not walls," Ma told the audience at his Saturday concert for sister cities in Mexico and the U.S.

Yo-Yo Ma Blasts Trump at Concert on Mexican Border: 'A Country Is Not a Hotel, and It's Not Full'

“In culture we build bridges, not walls,” Ma, 63, said before the crowd in Laredo, Texas, where he played next to the Juarez-Lincoln International Bridge, which connects Laredo to Nuevo Laredo, Mexico.

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According to NPR, he played in both cities on Saturday as part of a “Day of Action” during his ongoing Bach Project, an international tour of Johann Sebastian Bach’s cello suites.

The performances, according to Ma’s website, are “motivated by” both Ma’s musical mastery and “Bach’s ability to speak to our common humanity at a time when our civic conversation is so often focused on division.”

“I’ve lived my life at the borders between cultures, between disciplines, between musics, between generations,” Ma told the audience on Saturday.

“A country is not a hotel, and it’s not full,” he said.

Last week, while threatening to close the border with Mexico, Trump tweeted, “Our Country is FULL!”

Image zoom President Donald Trump Evan Vucci/AP/REX/Shutterstock

Ma also read Emma Lazarus’ poem “The New Colossus,” which famously adorns the Statue of Liberty.

He was also presented with a key to Laredo by the city’s mayor, who called Ma “the greatest cellist in the world,” according to CNN.

“His visit reminds us of how culture connects all of us,” Mayor Pete Saenz said.

The president has made restricting immigration, both legal and illegal, a centerpiece of his administration. Earlier this year he declared a national emergency to empower him to fund a border wall with Mexico, which Congress had rejected.