French President Emmanuel Macron said he has agreed with Iran's President Hassan Rouhani to seek conditions to resume discussions over Iran's nuclear ambitions, after Iran announced plans to break an international agreement and increase production of enriched uranium.

In 2015, Iran, the United States, China, France, Germany, Russia and the United Kingdom agreed a deal on the issue, in return for the lifting of sanctions, but one year ago the US government withdrew and reimposed tight sanctions.

Iran now says it plans to exceed the agreed limit on uranium enrichment, a product that can be used for nuclear energy and weapons, although the country insists it is for non-military purposes.

"The president of the republic has agreed with his Iranian counterpart to explore by July 15 conditions to resume dialogue between the parties," said a statement from Macron's office, issued after an hour-long telephone discussion between the two leaders.

The statement added that Macron would keep talking to Iran's authorities and other involved parties to "engage in a de-escalation of tensions related to Iranian nuclear issue."

Under 2015's Joint Comprehensive Plan of Action, Iran agreed to allow international inspectors to monitor its nuclear activities, and to keep them within prescribed limits, in return for sanctions being lifted.

Iran was only permitted to produce low-enriched uranium and to stockpile it up to agreed limited amounts. But having already surpassed the agreed level of stockpiling, the country says it now intends to increase the strength of the enriched uranium, for use at a power station in Bushehr.

When Iran announced its intention to increase the enrichment program, US President Donald Trump warned that any such move could "come back to bite you like nobody has been bitten before".

Iran's Deputy Foreign Minister Abbas Araqchi blamed European countries for the current situation, saying they had not kept their own pledges under the deal, and gave the other signatories a 60-day deadline to help protect his country from US sanctions, while also insisting that his government wanted to salvage the deal.

Israel has expressed its concern, with Energy Minister Yuval Steinitz saying Iran had "begun its march ... toward nuclear weaponry", while Prime Minister Benjamin Netanyahu called Iran's announcement a "very, very dangerous step", and urged the European signatories not to agree to Iran's requests.

The developments come amid an atmosphere of increasing tension in the Gulf region. Recently, Iran brought down an US drone, and last week British special forces boarded the oil tanker Grace 1 taking Iranian oil to Syria, off the coast of Gibraltar, contrary to European and US sanctions against Syrian.

Iran said the move was an "extraterritorial sanction" and had been carried out by the British at the request of the US.