Renewed US sanctions against Iran would impact European companies that have business in Iran. Meanwhile, European governments have vowed to safeguard the interests of their companies.

European trade and investment have flowed into Iran since the sanctions were lifted in January 2016. But businesses are told to wind down their operations in Iran because of the new sanctions that will be imposed by the United States. 

Germany is one of Iran's largest trading partners and the impact on its business seems immediate.The newly appointed US Ambassador to Germany Richard Grenell has called on all German companies to immediately wind down their operations with Iran.

For now, around 21 companies from five European countries have business in Iran, including Siemens, Volkswagen and Airbus. The question for them is how they can maintain business and what support they will need from the EU to continue.

"If they have business in the United States, they face the prospect of the sanctions against the business arm in the United States if they stay in Iran," said Cornelius Adebahr, Associate Fellow at German Council of Foreign Relations. "The question is can they and the European governments find a way to only abide by the EU law because they are European companies. This is something that needs to be worked out in the coming months."

The US Treasury Department says there will be a "wind down" period of 90 to 180 days for existing Iran contracts.

What comes next will be a lot of talks and negotiations, not only asking Iran to stay in the deal, but also to maintain the economic exchanges between Europe and Iran.