UK Foreign Secretary Boris Johnson vowed Monday that the UK would consider how to help European firms maintain confidence in doing business in Iran.

The UK and France are determined to preserve the essence of the Iran nuclear deal, Boris Johnson said.

"What we are going to do tomorrow in Brussels is we are going to have a conversation about what we can do to help UK firms, European firms have some confidence that they can still do business," Johnson said.

The UK prime minister said earlier that it was in both the UK and Iran's national security interests to support the deal and welcomed President Rouhani's public commitment to abide by its terms, emphasizing that it is essential that Iran continues to meet its obligations.

READ MORE: UK Welcomes Iran's Intention to Keep Nuclear Deal After US Exit — Downing Street

Europe and France have earlier discussed with the US the possibility of further exemptions for European companies that could be affected by US economic sanctions on Tehran in order to "defend their economic interests," as a number of French enterprises, including Total, Renault and Sanofi, are operating in Iran.

Customs Partnership After Brexit

"I think the prime minister's position that I've now twice applauded is completely right," Johnson stated, speaking about Theresa May's position on leaving the EU's customs union.

Previously, Prime Minister Theresa May stated that the UK would withdraw from the EU's customs union and the "customs partnership," which would see Britain primarily collect tariffs on behalf of the EU in order to preserve trade with the bloc.

At the same time, Theresa May on May 13 stated that she could be trusted to deliver Brexit, but that it could not be done without compromises on all sides.