President Trump warned Monday that new evidence of Iran's past effort to develop nuclear weapons is "not acceptable" and said he would be deciding in the next two weeks whether to abandon the Iran nuclear agreement or renegotiate it.

"That is just not an acceptable situation," he said just moments after Israeli Prime Minister Benjamin Netanyahu said he has proof of Iran's past "secret" weapons program.

But Trump refused to say what his next step would be and said it's still possible he could seek a renegotiation of the deal instead of leaving it altogether.

"We'll see what happens," he said at the White House. "I'm not telling you what I'm doing, but a lot of people think they know. And on or before the 12th we'll make a decision."

"That doesn't mean we won't negotiate a real agreement," he added.

Still, Trump signaled that leaving the deal was also possible. The U.S. has pushed to strike a new deal that covers Iran's ballistic missile activity and its support for destabilizing events in the region.

Trump said Israel did the right thing by announcing its findings today.

"I think it sends the right message," Trump said when asked for his reaction.

"You know, in seven years, that deal will have expired and Iran is free to go ahead and create nuclear weapons," he said. "That's not acceptable. Seven years is tomorrow. That's not acceptable."

Trump added that after sending Iran billions of dollars in cash as part of the agreement, "You know what we got? We got nothing."

This story was corrected to say Netanyahu was talking about Israel's past nuclear weapons program.