After outlining the terms of new oil contracts in a future post-sanctions era, the Iranian Oil Ministry said it hasn't seen any interest from U.S. companies.

Iranian Oil Minister Bijan Zangeneh said "all international" energy companies can present bids for projects in Iran's oil industry, though some are remaining on the sidelines.

"We have received no requests from any American company so far," he said.

Claudio Descalzi, the chief executive officer of Italian energy company Eni, was among the hundreds of representatives who joined Italian Foreign Minister Paolo Gentiloni on an official visit to Tehran last week. Eni had a $550 million deal to help Iran develop its Darkhovin oil field, expected to produce 160,000 barrels per day, before suspending operations in 2010 under sanctions pressure.

Royal Dutch Shell confirmed in June it was probing "potential areas" of business cooperation in Iran.

A July nuclear agreement between the five permanent members of the U.N. Security Council, plus Germany, and Iran could release that pressure on the Iranian oil sector.

Sanctions imposed on the Iranian energy sector in response to its nuclear program resulted in a real gross domestic product contraction of 5.8 percent last year, though the country emerged from recession in early 2015.

The Iranian oil minister last week said new contracts for potential players will be formally outlined during an investment conference scheduled in London in December. Under the new terms, the National Iranian Oil Co. will set up joint ventures with foreign companies, which will be paid with a share of the output.

Most international oil companies said they're still minding sanctions targeting Iran's energy sector. Members of a skeptical U.S. Congress are reviewing the nuclear deal amid a push for approval from President Barack Obama.