New York, New York - First Lady Melania Trump pressed the cause of children caught in conflict as she chaired a UN Security Council meeting Monday as the US-Israeli war against Iran raged.

Ambassadors from all of the Security Council's members, including Washington's rivals Russia and China, lined up to meet with Trump, representing the US as it took over the monthly rotating presidency of the Security Council.

She opened the meeting with a strike of a ceremonial gavel before thanking Britain for its month-long presidency, and spoke again later, honoring US service members killed in the war on Iran.

"To the families who have lost their heroes who sacrifice their lives for freedom, their bravery and dedication will always be remembered," Trump said before the packed chamber.

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"Enduring peace will be achieved when knowledge and understanding are fully valued within all our societies," she added. "Societies ruled by knowledge and wisdom are therefore more peaceful."

Moments later, the First Lady said "the US stands with all of the children throughout the world. I hope soon peace will be yours" – without referring directly to the attacks across the Middle East.

Ahead of the meeting, Iran's ambassador to the UN, Amir Saeid Iravani, said, "It is deeply shameful and hypocritical that on the very first day of its presidency of the Security Council, the United States convened a high-level meeting on protecting children."

She was warmly received by the countries represented in the Council, however, with Greece's ambassador Aglaia Balta saying, "Thank you, madam president," while France's envoy compared her to the celebrated former first lady and activist Eleanor Roosevelt.

Even Russia joined the chorus of polite praise, avoiding any mention of Iran, which was mentioned only by Council member and Washington's staunch ally, Bahrain.

"I wish you all strength and resolve to succeed in preserving peace and security throughout the world," Trump said as she closed the two-hour meeting.

Stephane Dujarric, spokesperson for the UN secretary-general, confirmed that Trump's appearance was the first time a first lady – or first gentleman – had presided over a Security Council meeting.

President Donald Trump's third wife has dabbled in diplomacy before, notably to try to secure the release of Ukrainian children abducted by Russia.

Political and financial tensions have mounted between the US and the United Nations in recent years, with Washington chafing at its role as the main contributor to the body's cash-strapped budget.

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Many observers say the US president intends to bypass the Security Council with his new "Board of Peace," which held its inaugural session in Washington last month.

Several countries pledged funds and personnel to rebuild Gaza, which has been destroyed by a brutal Israeli assault that has been staunchly supported by the US.

At the meeting, Trump repeated his stance that the UN had failed in its mission.

Since returning to the White House last year, the president has withdrawn support from several major UN agencies, including the World Health Organization.