Iran's ambassador to Mexico, Abolfazl Pasandideh, said late on Thursday the squad had still not received their US visas but these were granted overnight, the White House official said.
A spokesman for Iran's World Cup federation could not immediately be reached for comment.
The US had not yet issued visas to some members of the Iran team's technical and administrative staff, the semi-official Fars news agency reported on Friday.
"Visas for some members of the national team's technical and executive staff have not yet been issued, and the US embassy has so far refused to issue them," it said, without citing a source.
The Iran war has turned the World Cup – the biggest global sporting event – into a geopolitical contest, with both sides appearing to use the tournament for political posturing.
It is the first World Cup, since its inception in 1930, in which a host nation is set to receive a country it is at war with.
Tehran negotiated a last-minute move of the team's base from Arizona to Tijuana in Mexico due to the visa issues and a growing feeling in Iran that the squad’s presence in the United States should be kept to a minimum.
They are scheduled to land in Tijuana early on Sunday.
Iran are due to play their first Group G match on June 15th against New Zealand in Los Angeles, where they will also face Belgium before taking on Egypt in Seattle.
The US had never formally said it did not want the Iranian team to stay on its territory, Ambassador Pasandideh said.
However, Secretary of State Marco Rubio told lawmakers on Tuesday that the US would not allow Iran to include in its World Cup delegation individuals linked to the Islamic Revolutionary Guards, a powerful branch of the Iranian armed forces.
Mehdi Taj, president of Iran's football federation, was denied entry for the tournament draw in Washington in December. He is a former commander in the Revolutionary Guards.
Iran's desire to compete in the World Cup underscored its efforts to reach a resolution in the war with Washington, Pasandideh said.
"Iran's participation in the World Cup -- even on the soil of what is seen as its enemy -- shows that Iran seeks peace," Pasandideh said, speaking through a Spanish interpreter at the Iranian embassy in Mexico City.
Progress in peace talks between Iran and the US has been slow, with both sides seemingly inching toward an interim agreement even as they continue to carry out military strikes.
