As the United States steps up its push for tough new sanctions against Iran, a top American diplomat said Thursday that hopes of a deal with Iran to curb its nuclear ambitions are fading.

“What’s happening is that Iran is headed in the direction of further provocation, further enrichment,” U.S. Ambassador to the International Atomic Energy Agency Glyn Davies told CNN’s Christiane Amanpour.

“They (Iran) refuse to take steps that are even in their own interest, if they’re to be believed,” he said. “So right now, what option do we have except to pursue sanctions in the U.N. context and work with our partners to try to bring this to a reality?”

Davies, though, said the world’s patience with Iran is running out. “It’s becoming quite clear that they’re preserving at least the option of developing a nuclear program. And we want all nations of the world to take note of this and draw the right conclusion,” he said.

“There really is only one way to go right now, only one way to focus Iran on the need to make different decisions, and that is by putting pressure on them.”