Washington has expressed its regret over Egypt's recentdecision to renew direct flights between Cairo and Tehran, after more than 30 years.
The two nations have reportedly agreed to see 28 weekly flights between them – 14 in each direction.
The State Department spokesman Mark Toner called on all nations not to pursue financial dealings with Iran ,as long as it falters on its international obligations.
"We continue to urge all countries – including Egypt – not to pursue any new business deals until Iran complies with its international obligations," Toner said.
"Given the current atmosphere... we're trying to discourage this kind of engagement with Iran, until it owns up to its international obligations," he stressed.
Egypt is one of the United States' most important allies in the Middle East.
Hamid Baghaei, an Iranian vice president and the head of culture and tourism, told Tehran State Television that the agreement was "one of the most valuable economic agreements that have been signed between Iran and Egypt over the past 30 years," adding that it could be a first step toward issuing visas to Egyptian and Iranian citizens and otherwise furthering ties between the two usually states.
Still, Egyptian Foreign Ministry Spokesman Hossam Zaki stressed that business ties aside, political ties were a different matter.
Egypt originally cut ties with Iran shortly after the Iranian Revolution of 1978.
AFP contributed to this report