Human Rights Watch said Tuesday an Israeli strike in Lebanon that killed seven first responders was "an unlawful attack on civilians", and urged Washington to suspend weapons sales to Israel.

The Israel-Lebanon border area has witnessed near-daily exchanges between the Israeli army and Hamas ally Hezbollah since the Palestinian militant group attacked southern Israel on October 7 sparking war in Gaza.

"An Israeli strike on an emergency and relief center" in the southern village of Habariyeh on March 27 "killed seven emergency and relief volunteers" and constituted an "unlawful attack on civilians that failed to take all necessary precautions", HRW said in a statement.

"If the attack on civilians was carried out intentionally or recklessly, it should be investigated as an apparent war crime," it added.

The Israeli military did not immediately comment when contacted by AFP.

But at the time the military said the target was "a military compound" and that the strike killed a "significant terrorist operative" from Jamaa Islamiya, a Lebanese group close to Hamas, and other "terrorists".

HRW said in the statement that it found "no evidence of a military target at the site", and said the Israeli strike "targeted a residential structure that housed the Emergency and Relief Corps of the Lebanese Succour Association, a non-governmental humanitarian organisation".

Jamaa Islamiya later denied it was connected to the emergency responders, and the association told AFP it had no affiliation with any Lebanese political organisation.

HRW said "the Israeli military's admission" it had targeted the center in Habariyeh indicated a "failure to take all feasible precautions to verify that the target was military and avoid loss of civilian life... making the strike unlawful".

The rights group said those killed were volunteers, adding that 18-year-old twin brothers were among the dead.

"Family members... the Lebanese Succour Association, and the civil defense all said that the seven men were civilians and not affiliated with any armed group," it added.

However, it noted that social media content suggested at least two of those killed "may have been supporters" of Jamaa Islamiya.

HRW said images of weapons parts found at the site included the remains of an Israeli bomb and remnants of a "guidance kit produced by the U.S.-based Boeing Company".

"Israeli forces used a U.S. weapon to conduct a strike that killed seven civilian relief workers in Lebanon who were merely doing their jobs," HRW's Lebanon researcher, Ramzi Kaiss, said.

The rights group urged the United States to "immediately suspend arms sales and military assistance to Israel given evidence that the Israeli military is using U.S. weapons unlawfully".