Iran are due to play their three group-stage games in the US - two in Inglewood, California, then in Seattle - from June 15-26. Cities in Canada and Mexico also will host some of the 104 games.
The US and Israel have targeted Iran in coordinated attacks since Saturday that killed Supreme Leader Ayatollah Ali Khamenei and dozens more senior officials.
It provoked an Iranian response that aimed missiles at US allies including 2022 World Cup host Qatar and Saudi Arabia, which FIFA has picked to stage the 2034 edition.
"What is certain is that after this attack, we cannot be expected to look forward to the World Cup with hope," said Iran's top soccer official Mehdi Taj, a vice-president of the Asian Football Confederation.
It is unclear if the state-backed Iranian soccer federation will refuse to send their team to the 48-nation tournament that starts June 11, or the US government could effectively block them.
FIFA has declined comment since Saturday, when secretary-general Mattias Grafström said it would "monitor developments around all issues around the world."
Iran, one of the best national teams in Asia, have qualified for six of the past eight World Cups.
They are ranked No.20 in FIFA and have not been lower than No.24 since the last World Cup in Qatar.
Iran, who were among the second-seeded teams in the World Cup draw held in Washington, D.C. in December, are due to start against New Zealand, then play Belgium and finish against Egypt.
Should Iran pull out, the likely replacement from Asia will be Iraq or the United Arab Emirates.
Iraq and the UAE were effectively the ninth and 10th-ranked Asian teams through the various qualifying groups and advanced to a two-leg playoff last November.
Iraq won 3-2 on aggregate - eliminating the UAE - to advance to the intercontinental playoffs in Mexico and, on March 31, they are scheduled to play an elimination game against Bolivia or Suriname with a World Cup place at stake.
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