UNITED NATIONS (Reuters) - France’s president said on Wednesday that the United States’ sanctions policy on Iran could force Tehran to negotiate, but only if European powers are able to ensure it sticks to a 2015 nuclear deal that is preventing hard-liners from taking control.

France's President Emmanuel Macron addresses the 73rd session of the United Nations General Assembly at U.N. headquarters in New York, U.S., September 25, 2018. REUTERS/Carlo Allegri

U.S. President Donald Trump used a session on nonproliferation of weapons of mass destruction at the U.N. Security Council to defend his May 8 decision to abandon the nuclear pact under which Tehran limited its nuclear program in return for the easing of U.S., European and international economic sanctions.

The core U.S. sanctions that seek to choke off Iran’s oil exports, the lifeblood of its economy, will resume in early November, and Trump promised that “after that the United States will pursue additional sanctions, tougher than ever before, to counter the entire range of Iran’s malign behavior.”

In contrast, his closest European allies, France, Britain and Germany, along with China and Russia, are trying to salvage the accord by developing ways to bypass U.S. sanctions so that Iran can still receive oil revenue, giving it an incentive to stay in the agreement.

“Perhaps because we’re able to keep this multilateral framework (nuclear deal), avoid the worst and act as a mediator, while the U.S. sanctions create pressure and reduce the amount of money available for Iran’s expansionism, that can accelerate the process we want,” French President Emmanuel Macron told reporters.

“As long as the deal serves our interests, we will remain in the pact,” Iranian President Hassan Rouhani told reporters in New York. “Remaining members of the deal have taken very good steps forward, but Iran has higher expectations.”

The European powers and the United States agree that a broader deal needs to be struck with Iran that tackles its long-term nuclear activities, ballistic missile program and to curb its regional influence. They accuse Iran of supporting destabilizing proxies in Lebanon, Syria, Yemen and Iraq.

However, Macron warned that unlike North Korea, Iran was not ruled by one dictator and diehard elements were determined to kill the nuclear deal.

“The main risk of the pressure strategy is that it pushes Iran to restart its nuclear activities ... so if we want a chance for this pressure on Iran to produce results, then we need to make sure it doesn’t opt for the worst option.”

Trump asked the Security Council to work with Washington to “ensure the Iranian regime changes its behavior and never acquires a nuclear bomb.”

But highlighting the differences in approach, the European Union’s foreign policy chief, Federica Mogherini, said a so-called Special Purpose Vehicle (SPV) under consideration to facilitate trade with Iran could be in place “before November.”

The SPV, slammed by U.S. officials, would create a sort of barter system, similar to one used by the Soviet Union during the Cold War, to exchange Iranian oil for European goods without money changing hands and avoiding banking exchanges.

Whether that is enough to keep Iran on board remains to be seen. Facing a collapsing economy at home, Rouhani is in a bind and is being pressed by hard-liners to abandon the deal as its economic benefits evaporate.

Big European companies have already pulled out and Iranian oil exports have fallen sharply even before Nov. 4 when the next round of sanctions come into effect.