PARIS — The United States lost its vote at Unesco on Friday, two years after cutting off its financial contribution to the organization over the admission of Palestinians as full members. The move undermined America’s ability to exercise its influence in countries around the globe through the United Nations agency’s educational and aid programs, according to Western diplomats and international relations experts.

Under Unesco’s constitution, any country that fails to pay dues for two years loses its vote in the Unesco general assembly. The United States ceased all support for the agency in 2011, in response to a vote at Unesco giving Palestinians full membership. Congress enacted laws in the 1990s decreeing that the United States stop providing money to any United Nations agency that accepts Palestinians as full members.

It was the first time that the United States had voluntarily given up its vote in an organization it belongs to, diplomats here said.

“I deeply regret this,” Irina Bokova, Unesco’s director general, said in an interview Friday at the agency’s headquarters here. “This is not some kind of punishment on behalf of Unesco for nonpayment. It’s just our rules.