BRUSSELS — Javier Solana, a former secretary general of NATO who played a central role in negotiations over Iran’s nuclear program when he was the European Union’s foreign policy chief, has been denied electronic authorization to enter the United States because of a visit to Iran in 2013.
Mr. Solana said on Monday that his renewal application on the Electronic System for Travel Authorization, or ESTA — which determines the eligibility of visitors from certain countries to travel to the United States without having to apply for a visa — had been rejected for the first time. He said he would apply for a visa instead, a more cumbersome and expensive process.
Mr. Solana, 75, a Spanish citizen whose travel authorization problem was first reported by the daily El País, said that he considered it “to be more bureaucratic than political.”
In 2016, the Obama administration, responding to restrictions decided in Congress, tightened requirements to prevent citizens of 38 countries who had traveled to Iran, Iraq, Sudan or Syria after March 1, 2011, or those who are citizens of those countries, from coming to the United States under the online visa-waiver program.
Instead, such travelers are required to go through the full vetting process required to get a visa, including an in-person interview at a United States Embassy or Consulate.
But visa waivers can also be granted on a case-by-case basis for those who have traveled to Iran as journalists, aid workers or government representatives.
Mr. Solana said that he was last in Iran in 2013, when he was invited for the inauguration of President Hassan Rouhani. Mr. Solana had no official government post at that time.
The Trump administration has been especially hostile to Iran, withdrawing from the 2015 Iran nuclear deal that Mr. Solana was instrumental to initiating during his time as European foreign policy chief, a job he left in 2009.
Citizens of Spain do not usually need visas to enter the United States for fewer than 90 days. The ESTA authorization, available to citizens of 38 countries, including Australia, Britain, New Zealand and most of the European Union, and which must be requested at least 72 hours before travel, normally means that there are no surprises at border entry points.
Mr. Solana, who also served as Spain’s foreign minister, had been scheduled to attend an event in Washington.
A press officer for the American Embassy in Madrid said that he could not comment on individual cases, but that ESTA rules were clearly detailed on the website of the Department for Homeland Security.