HAVANA — “Being here is like heaven,” the composer and musician David Amram said after watching the singer Daymé Arocena light up the crowd at the Casa de la Cultura here on Friday. “Like getting a second chance at life, and most people don’t even get a first chance.”

Mr. Amram, who first visited Cuba in 1977, returned last week for the 33rd International Jazz Plaza Festival, a six-day event that drew Cuban jazz veterans like Chucho Valdés and the Orquesta Aragón, as well as rising stars like Ms. Arocena and Yissy García. Despite tightened restrictions on travel to Cuba from the United States, the festival relied heavily on American performers, including Joe Lovano, whose first trip to Cuba was in 1986, and Randy Weston and Dee Dee Bridgewater, who were visiting for the first time.

However this year’s event took place under a cloud of renewed uncertainty for many Cuban musicians. Since the Trump administration’s withdrawal of diplomats from Havana in September, the United States Embassy here has stopped processing visa applications from Cubans, who have taken to traveling to a third country to apply for visas to the States.

But visiting musicians like Mr. Amram and Ms. Bridgewater spoke of their role as cultural ambassadors who could touch hearts in spite of political borders. “My being here is my way of saying, yes, Cuba, yes, you all amazing musicians, I stand with you,” Ms. Bridgewater said at a news conference, raising her fist in solidarity. “I am your sister in music and that is all I care about.”