The EU has been pulled into discussions with Iran to help them secure better terms from the United States, following last year's nuclear deal.
EU foreign policy chief Federica Mogherini, whose team of seven commissioners was the biggest to visit Tehran in more than a decade, said it was in Europe's interest to make sure European banks felt confident to do business in Iran.
The high profile visit also involved discussions of a significant expansion in economic and energy ties.
Iranian foreign minister, Mohammad Javad Zarif, welcomed EU support in Iran's bid to join the WTO and spoke of a new beginning in relations between the two nations.
Iran hopes that the meeting with the EU will enable it to gain financial concessions from the US.
They have requested that the EU put pressure on the US to let them into the global financial system and join the World Trade Organization.
Following the nuclear deal last year, nations like the US and EU have lifted most sanctions on Iran in return for curbs on its nuclear program.
Some sanctions do remain however, and US banks are prohibited from doing business with Iran directly or indirectly because the government still accuses Tehran of supporting human rights violations and supporting terrorism.
There are also some European banks that fear falling foul of US sanctions imposed by Washington. In addition to this, Mogherini commented that the EU would continue to stand firm against the Iran's alleged human rights violations.
"Today is a new beginning in Iran and EU relations. We hope this co-operation between the Iranian nation and European Union brings about shared interests and global development," Mr Zarif said in a statement.
The White House however, pointed out last week that there was no intention of allowing Iran into the world financial institution.