While he did not make a commitment to end imports of Iranian crude to avoid USA sanctions, he said Japan would "carefully analyze the impact" the US withdrawal would have.
The Treasury imposed the sanctions on nine Iranians and companies it said were operating a corrupt currency exchange network in the United Arab Emirates with complicity from Iran's Central Bank.
The big question at this point is how disruptive unilateral sanctions from the USA will be to Iranian oil flows.More news: Trump lists reimbursement to Michael Cohen; ethics office says disclosure was required
In an ironic twist, President Donald Trump's diplomatic progress in North Korea may have played a major role in his decision to withdraw from the Iran nuclear agreement.
White House National Security adviser John Bolton on Sunday said USA sanctions on European companies that do business with Iran were "possible, but Secretary of State Mike Pompeo said he remained hopeful Washington and its allies could strike a new nuclear deal with Tehran". Iran is still sticking to its nuclear commitments, according to IAEA inspectors.
In other sectors, French carmaker PSA Peugeot Citroen agreed in 2016 to open a plant producing 200,000 vehicles annually in Iran, and says it is studying the implications of the US move.
The investors are anxious that renewed sanctions against Iran, a major oil producer, could lead to supply disruptions. A muted reaction from Iran would paint the U.S.as the aggressor, allowing Iran to more latitude to skirt USA enforcement.
The oil price is at its highest since late 2014 and on track for its fourth consecutive quarterly gain, the longest such stretch for more than 10 years. There will be a 90-day and 180-day wind down period before sanctions really start to bite, which puts the deadline at early November.More news: Battlefield V name confirmed as EA sets May 23 reveal
Crude prices fell in a see-saw session on Friday, retreating after early gains as it looked likely that USA allies would push to maintain a deal with Iran, which could keep that country's crude exports on global markets.
Since the Iran nuclear deal came into effect, Iranian oil output increased from 2.7 million to 3.8 million barrels per day.
According to Credit Suisse, the last time Iran was subject to worldwide sanctions (between 2010 and 2016) its oil exports fell from 2.2 million barrels per day to around 1.1 million barrels.
Goldman Sachs said the planned unilateral US sanctions against Iran would likely have a "high level of efficiency". He added that condensate, a super-light form of crude oil that was excluded in the last round of sanctions, may well be included. Reuters news agency says Shell and some other European firms with big operations in the USA prefer to push for USA waivers on a case-by-case basis.
May's spokeswoman said May had told Trump that Britain and its European partners remained "firmly committed" to ensuring the deal was upheld as the best way to prevent Iran from developing a nuclear weapon.More news: EU's Tusk asks: 'With friends like Trump, who needs enemies?'
While the United States could "totally d***" the Iranians, it would requires over a "couple of million" men, led to unspeakable causalities and require a full-scale invasion of Iran.