Al-Qaeda's Syria affiliate said on Saturday it would prosecute members involved in an shoot-out in northwest Idlib province that killed at least 20 members of the country's Druze minority.

In an official statement published on Twitter, Al-Nusra Front sought to allay fears of further attacks on minorities, saying that some of its members acted "in clear violation of the leadership's views".

On Thursday, residents of the village of Qalb Lawzah protested after a Tunisian Al-Nusra leader tried to seize a Druze man's home, accusing him of being loyal to the Syrian regime, the Syrian Observatory for Human Rights said.

"The Tunisian leader gathered his men and accused the Druze residents of the village of blasphemy and opened fire on them killing at least 20 people, among them elderly people and at least one child," said Observatory head Rami Abdel Rahman.

In its statement, Al-Nusra said it had immediately despatched a committee to Qalb Lawzah to "reassure the residents that what happened was unjustifiable".

"This village and its people are still safe under our protection and in areas under our control. Everyone who was involved in this incident will be referred to an Islamic court and will be held accountable," the jihadist group said.

A vast majority of Idlib province is under the control of a rebel alliance that includes Al-Nusra.

The shoot-out comes less than a month after Al-Nusra's chief tried to play down fears that it would target minorities.

Abu Mohamed al-Jolani said in a televised interview that his group would protect minorities who "leave their religion and leave (Syrian President) Bashar al-Assad".

Extremist groups in Syria, including Al-Nusra and its jihadist rival the Islamic State group, have been accused of targeting minorities and civilians.