French President Emmanuel Macron said Thursday that U.S. strikes on Iran's nuclear facilities were "genuinely effective," but the "worst-case scenario" would be if Tehran now exits the global non-proliferation treaty.

"The worst would be that the consequence of this is Iran's exit from the Non-Proliferation Treaty (NTP) and therefore, ultimately, a drift and a collective weakening," Macron told journalists after an EU summit in Brussels.

Macron said that in a bid to maintain the treaty – which is meant to limit the spread of nuclear weapons – he would speak in the coming days to the five members of the United Nations Security Council.

Those talks had already kicked off with a call with President Donald Trump on Thursday, in which Macron said he informed his U.S. counterparts of contacts Paris had with Tehran in "the last few days and hours."

"Our hope is that there will be a real convergence of views," Macron said, adding that the aim was "that there should be no resumption" of nuclear buildup by Iran.