WASHINGTON (Reuters) - The United States will not go forward with planned food aid to North Korea, the White House said on Friday, after the impoverished nation's unsuccessful launch of a long-range missile which Washington had warned would have consequences.

"Their efforts to launch a missile clearly demonstrates that they could not be trusted to keep their commitments," White House National Security Council spokesman Ben Rhodes told reporters traveling with President Barack Obama to Florida.

"Therefore, we are not going forward with an agreement to provide them with any assistance," he said, warning that North Korea faced additional sanctions if it defied the international community again by taking further "provocative" steps.

North Korea said the missile launch had failed earlier on Friday.

Washington had offered in February to consider providing North Korea with nutritional aid in return for its suspension of uranium enrichment activities and other movement toward the de-nuclearization of the Korean peninsula.

But it had repeatedly cautioned that the test of the long-range missile would jeopardize food aid, and said it would begin working on "additional steps" with other world powers to dissuade Pyongyang from further acts of provocation.

"Today we will begin consultations at the United Nations Security Council about how to deliver a message to the North Koreans that the international community rejects this launch and is prepared to take additional steps, particularly if North Korea continues to go down the road of taking provocative actions," Rhodes said.

North Korea, embarrassed by the failure of the much-hyped rocket launch, is now widely believed to be weighing undertaking its third nuclear test in order to show its military strength.

"If they continue to take additional provocative actions, we of course have to continue to look at ways in which we could tighten sanctions on the North Koreans, and take additional steps to apply pressure on the regime," Rhodes said.

(Editing by Vicki Allen)