Deputy foreign minister Abbas Araghchi told London's Chatham House that US President Donald Trump's hostility towards the Joint Comprehensive Plan of Action (JCPOA) was creating a "destructive atmosphere" that meant businesses were afraid of dealing with Iran.

"As far as Iran is concerned, JCPOA is not a successful story," he said.

"Iran is not benefiting from sanction lifting in full."

Under the JCPOA, sanctions were lifted in return for a commitment not to pursue a nuclear bomb, but Iran claims it is not reaping the rewards despite complying with the deal.

The JCPOA was struck between Iran and Britain, China, France, Germany, Russia and the US, then led by Barack Obama.

But Trump called it the "worst deal ever" and has demanded that European partners "fix the terrible flaws" or he would re-impose sanctions, although he has so far issued "waivers" upholding the deal.

"It is like poison for the business community," said Araghchi.

"I don't think the deal can survive in this way. Even if the waivers are extended... if companies and banks are not working with Iran, we cannot remain in a deal that there is no benefit for us."

He accused Trump's administration of violating JCPOA "on a daily basis almost."

"All these statements by President Trump are a violation of the deal, of the letter and the text of the deal.

"We have now a destructive atmosphere."

Tehran would not accept any changes to the deal, including attempts to tie it to Iran's ballistic missile programme, he said.

Much of the criticism of the deal revolves around its so-called "sunset" clauses, which detail when the various restrictions imposed on Iran's nuclear programme expire.

Araghchi denied that Iran would be able to build nuclear weapons after these provisions expire in 10-15 years time and insisted that Iran would not consider making the restrictions permanent.

"Iran's commitment in the JCPOA not to go for nuclear weapons is permanent," he said.

"To change these provisions and make these clauses permanent means killing of the deal.

"We accepted 10-15 years of restrictions for confidence building, it doesn't mean we have to build confidence forever, it's ridiculous."

If the deal did collapse, he warned the world would face "another nuclear crisis that would be very difficult to be resolved."