Congressional negotiators and European allies have one “last chance” to agree on new policies to confront Iran before President Trump withdraws from the nuclear deal, he warned Friday.

“I am waiving the application of certain nuclear sanctions, but only in order to secure our European allies’ agreement to fix the terrible flaws of the Iran nuclear deal,” Trump said in a Friday afternoon statement.

“This is a last chance. In the absence of such an agreement, the United States will not again waive sanctions in order to stay in the Iran nuclear deal. And if at any time I judge that such an agreement is not within reach, I will withdraw from the deal immediately.”

Trump also warned that countries have to decide whether they're working with the U.S. to change the deal, or against it.

"No one should doubt my word," he said. "I said I would not certify the nuclear deal — and I did not. I will also follow through on this pledge."

"I hereby call on key European countries to join with the United States in fixing significant flaws in the deal, countering Iranian aggression, and supporting the Iranian people," he said. "If other nations fail to act during this time, I will terminate our deal with Iran. Those who, for whatever reason, choose not to work with us will be siding with the Iranian regime’s nuclear ambitions, and against the people of Iran and the peaceful nations of the world."