"There is no indication that the envelope contained something dangerous or poisoned," Embassy spokesman Paul Patin said. "There is no indication that anyone is in danger or hurt."
A Paris police official said the employees were "unwell" after the incident. The official, who was not authorized to be publicly named because an investigation was under way, did not elaborate on the workers' condition.
Mailroom employees identified a suspicious letter and the embassy alerted the French authorities, Patin said.
"The letter is being examined by chemical experts. The two people who handled the letter are being examined by medical authorities" at the Paris hospital Hotel Dieu, Patin told The Associated Press.
The embassy could not immediately provide further information about where the letter came from or what was suspicious about it, or the nationalities of the employees.
The mailroom is in the main building of the embassy, located just off the Champs-Elysees and not far from the French presidential palace.
The embassy, which is always surrounded by layers of security, remained open after the incident, and employees were entering and exiting the building as usual Friday afternoon.