Israeli Prime Minister Benjamin Netanyahu urged Europe on Monday to impose "automatic sanctions" on Iran for accumulating more low-enriched uranium than permitted under its 2015 nuclear deal with major powers.
"I say again that Israel will not allow Iran to develop nuclear weapons," Netanyahu said, according to a statement from his office.
"On this day I also call on all European countries to stand behind their commitments. You committed to acting the moment Iran violates the nuclear agreement, you committed to activating the mechanism for automatic sanctions that was set in the (UN) Security Council," he said.
A European diplomat told Reuters there was a mechanism under the agreement to deal with "any inconsistencies", and it would be up to a joint commission of signatories to decide next steps.
Iran's move was the first major step in violation of the deal since the United States pulled out of it more than a year ago and reimposed tough economic sanctions on Iran.
Earlier on Monday Israel's energy minister accused Iran of pursuing "nuclear blackmail" by stockpiling more low-enriched uranium than permitted under the deal but said continued international pressure would cause Tehran to back down.
"It's a blatant violation of the agreement," Yuval Steinitz said on Kan public radio. "Iran is carrying out nuclear blackmail. It is saying to the world, 'Look how close we are to a nuclear weapon'.
"Iran's economy is collapsing …they are under atomic pressure, so they are taking unbalanced actions," he added. "If the pressure continues, and the world doesn't give in, they will give it up."