"Regarding the fifth step, decisions had already been made... but considering the current situation, some changes will be made in an important meeting tonight," foreign ministry spokesman Abbas Mousavi said in televised remarks two days after the US killed a top Iranian general in a drone strike.

"In the world of politics, all things affect each other," he added.

Mousavi gave no indication as to what the next step would be nor when it would be announced.

The nuclear accord between Iran and the United Nations Security Council's five permanent members -- Britain, China, France, Russia and the United States -- plus Germany was agreed in 2015.

It has been hanging by a thread since the US withdrawal in May 2018, despite efforts to salvage it led by the three European nations that remain parties to the deal along with China and Russia.

The US on Friday killed Iranian general Qasem Soleimani in a drone strike near Baghdad international airport that raised fears of a new war in the Middle East.

Iran has vowed "severe revenge" for the killing of the commander of the Revolutionary Guards' foreign operations.

On Saturday, France urged Iran to stick to the landmark 2015 nuclear accord.

"France fully shares with Germany the central objective of de-escalation and preservation of the Vienna (nuclear) accord," Foreign Minister Jean-Yves Le Drian said.

With China, "we in particular noted our agreement... to urge Iran to avoid any new violation of the Vienna accord," he added.