The US "bears full responsibility for the repercussions of this aggressive attack on Iraq and Syria," the group said in a statement.

"Those who pour oil on the fire, we assure you that the region will not find stability, nor peace until the Zionist (Israeli) aggression, genocidal crimes and ethnic cleansing of the Palestinian people in the Gaza Strip ceases."

The United States launched air strikes against Iran-backed armed groups in Iraq and Syria, with President Joe Biden vowing more to come, in retaliation for a drone attack that killed three US soldiers in Jordan on Sunday.

The US military said it attacked a total of 85 targets at seven different sites in Syria and Iraq.

The strikes killed at least 23 pro-Iranian fighters in Syria, the Syrian Observatory for Human Rights war monitor said. In Iraq, they killed 16 people, including civilians, the Baghdad government said.

US and allied troops have been attacked more than 165 times in Iraq, Syria and Jordan since mid-October in a campaign waged by Iran-backed armed groups angered by US support for Israel in the war in Gaza.

The war broke out following Hamas's attack on Israel on October 7 that resulted in the deaths of more than 1,160 people in Israel, mostly civilians, according to an AFP tally based on official Israeli figures.

In response Israel launched a blistering air, land and sea offensive in Gaza that has killed at least 27,238 people, most of them women, children and adolescents, according to the Hamas-run territory's health ministry.