At least one analyst has downplayed the importance of crude to the overall economy.
Their trade ties may even be reinforced as Iranian cargoes would have to seek alternative export outlets, when the United States sanctions are reinstated.
Airbus, Siemens, Total, PSA and Fincantieri were among the multinationals launching investments in Iran, although the Islamic Republic's problems with financing its wish list kept a lid on enthusiasm.
France's Total became the first Western energy firm to sign a deal with Iran after the easing of global sanctions in 2016, agreeing to develop Phase 11 of the South Pars offshore gas field with a total investment of $5 billion.
The same problem faces French hotel chain Accor, which opened a hotel in Iran in 2015, as well as others in hospitality, such as Spain's Melia Hotels International and Rotana Hotels of the United Arab Emirates. "This is very important to develop our country", Rouhani said. S. allies would push to maintain a deal with Iran, which could keep that country´s crude exports on global markets.
However, traders remain on edge over the China-US trade spat, with the failure last week of talks in Beijing causing concern.
Though Trump's decision to leave what he called the "disastrous" deal was praised widely in Israel, the accord's other signatories - Britain, France, Germany, Russia and China - have signaled their commitment to upholding the pact.
The US withdrawal from the nuclear deal with Tehran on Tuesday is the first step in the American plan for a regime change in Iran carried out in accordance with the Iraqi scenario, Middle East expert Sami Ramadani told RT.More news: North Korea to dismantle nuclear site ahead of Trump-Kim summit
Mnuchin said that the new sanctions would allow countries doing business with Iran to wind down those activities in either 90 or 180 days, depending on the type of products being sanctioned.
Analysts said the recent rally in oil prices has been driven mostly by strong demand and limits on production.
"Oil is not a big problem".
"You're going to pay more because the rest of the world is seeing this burst in demand for transportation fuels", he says. "So, cutting imports from a single supplier will not be a problem", he added.
The sanctions come amid an oil market that has been tightening due to strong demand, especially in Asia, and as top exporter Saudi Arabia and No.1 producer Russian Federation have led efforts since 2017 to withhold oil supplies to prop up prices.
Mnuchin said US officials have had discussions with other countries about increasing production to offset the loss of oil from Iran.
The firm said it expects prices to rise another 10 percent.
"It's classic "buy on the bad news", said Ian Winer, director of trading at Wedbush Securities in Los Angeles, referring to the wider market's rally.