Washington DC - President Joe Biden blasted Donald Trump for describing Hezbollah as "very smart" even as the Lebanese militant group exchanges fire with Israel following the Hamas attack on the US ally.

During a campaign speech in Florida, Trump also falsely accused the Biden administration of bankrolling the Hamas assault as a result of a prisoner exchange deal with Iran, which has historically funded Hamas and Hezbollah.

In a post on X, Biden said that "our nation's support for Israel is resolute and unwavering. And the right time to praise the terrorists who seek to destroy them is never."

Trump had made his remarks to supporters in West Palm Beach as he was criticizing the White House.

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"You know, Hezbollah is very smart. They're all very smart," Trump said.

White House deputy press secretary Andrew Bates said Trump's remarks were "dangerous and unhinged."

Israel also reacted angrily, with Communications Minister Shlomo Karhi in a TV interview saying Trump could "obviously" not be trusted.

"It is shameful that such a person, a former president of the United States, aid propaganda and spreads comments that harm the spirit of IDF (army) fighters and the spirit of Israeli residents," Karhi said. "We don't need to deal with him or with the nonsense he says."

In a statement Thursday evening, Trump did not address his comment on Hezbollah but said Israel had "no better friend or ally... than President Donald J. Trump."

Biden's "weakness and incompetence has empowered and emboldened our enemies all over the World, and now, many lives have been so needlessly lost," the statement said.