In May, the Iranian tennis referee Adel Borghei received confirmation that he had secured a coveted slot at the United States Open. “Congratulations,” the letter started.

Borghei booked his travel, obtained a visa and worked several other tournaments until he arrived in the United States. He was scheduled to start work at the Open on Tuesday, in the qualifying rounds. Instead, he is in Florida, in limbo, unable to fulfill what he described as a dream assignment because of United States’ sanctions against Iran.

In an e-mail sent on behalf of Rich Kaufman, director of officials, the United States Tennis Association said “current United States law” prohibited the Open from “retaining the services of a resident of Iran.” The e-mail included an apology and expressed a hope that Borghei could work a future Open.

“This should not be about politics,” Borghei said in a telephone interview. “That’s what I have a problem here with. I don’t want to talk about politics. But they’re mixing up politics and sports.”