Iran players are still waiting to be issued with visas for the World Cup, says Iranian FA president Mehdi Taj.
Thousands of fans attended a departure rally for the squad in Tehran on Wednesday, before the tournament - co-hosted by the US, Canada and Mexico - starts on 11 June.
The US is at war with Iran, although the countries are in the midst of a month-long ceasefire.
Taj said the "visa issue has still not been resolved".
"Tomorrow or the day after, we will have a decisive meeting with Fifa. They must give us guarantees," he told state news agency IRNA.
"We have not received any account from the other side regarding who has been granted visas. No visas have been issued yet."
Iran are scheduled to play New Zealand on 15 June and Belgium on 21 June - both in Los Angeles - and Egypt in Seattle on 26 June. The team will be based in Tucson, Arizona.
The war has led to uncertainty around Iran's participation in the World Cup, but Fifa president Gianni Infantino said at Fifa's annual congress in Vancouver last month: "Of course, Iran will play in the United States of America."
Iran were the only country not represented at the congress after a delegation of Iranian FA (FFIRI) officials, including Taj, were turned away at the Canadian border.
Taj said the decision to return home was their own choice after what they felt was disrespectful treatment by immigration officials.
Canada's immigration minister told parliament that Taj's visa was cancelled while he was flying because of his links to the Islamic Revolutionary Guard Corps (IRGC).
US Secretary of State Marco Rubio has said that Iran players will be welcome at the tournament but individuals with links to the IRGC could face entry restrictions.
The FFIRI has since presented Fifa with a list of 10 conditions for their participation at the World Cup, including allowing players, coaches and officials who have completed military service with the IRGC to receive visas.
