"Secretary Kerry has talked directly to Foreign Minister [Laurent] Fabius about the trade delegation ... about how this is not helpful," Under-Secretary of State for Political Affairs Wendy Sherman told US lawmakers in Washington on Tuesday.
"Tehran is not open for business because our sanctions relief is quite temporary, quite limited and quite targeted," she said.
In a provisional agreement in November Iran agreed to downsize its nuclear programme in exchange for an easing of sanctions but the deal is not yet definitive.
Bosses of major French companies, including L'Oréal, Airbus, Total, GDF-Suez, Renault, Safran, Alcatel and Astom, met President Hassan Rowhani's chief of staff, Mohammad Nahavandian and members of the Iranian Chamber of Commerce during a visit to Iran on 2-5 February.
Pierre Gattaz, the head of the bosses' union, Medef, on Wednesday declared that the delegation was "perfectly aware of the sensitive, extremely sensitive, context on Iran", while the french foreign affairs ministry described the trip as "exploratory".
Finance Minister Pierre Moscovivi declared that it was a "gamble on the future" with the message "Fulfil your obligations and if one day you do things will go well."