Iran's foreign ministry on Monday rejected media reports accusing the country of involvement in the latest violence in Syria, which has left hundreds killed.

"This accusation is completely ridiculous and rejected, and we think that pointing the finger of accusation at Iran and Iran's friends is wrongly addressed, a deviant trend, and a hundred percent misleading," said foreign ministry spokesman Esmaeil Baqaei in a weekly press briefing.

A Syrian war monitor said Monday that security forces and allied groups had killed 973 civilians in a series of "massacres" in coastal areas and in the Latakia Mountains since March 6.

The Syrian Observatory for Human Rights said "the total number of civilian martyrs who were liquidated amounted to 973, including women and children", adding the "killings, field executions and ethnic cleansing operations" were ongoing in the wake of deadly clashes between security forces and Alawite gunmen loyal to toppled president Bashar al-Assad.

Israel on Sunday prepared to send a delegation to Doha for further talks on the Gaza truce, as Hamas called for an immediate start to negotiations on the ceasefire's second phase, which it hopes will lead to a permanent end to the war.

France has condemned violence in Syria targeting "civilians because of their faith, and prisoners", as a war monitor said more than 500 Alawites have been killed in recent days.

A French foreign ministry statement called on Syria's new authorities "to ensure that independent investigations can shed light on these crimes, and that the perpetrators are sentenced".

The leaders of Syria's three main Christian churches have issued a joint statement condemning "massacres targeting innocent civilians", following reports of mass killings of Alawite civilians by the security forces.

Syrian President Ahmed al-Sharaa called for national unity and peace on Sunday, after more than 1,000 people were reportedly killed in coastal Syria in the worst clashes since the overthrow of Bashar al-Assad.

The violence erupted on Thursday between the new security forces and loyalists of the former government along the Mediterranean coast in the heartland of the Alawite minority to which Assad belonged, before escalating into massacres against Alawite civilians that left hundreds dead.

Yemen's Iran-backed Houthis will resume attacks on Israeli shipping if aid supplies to Gaza do not resume in four days, the rebels' leader said on Friday.

"If the Israeli enemy continues after the first four days to prevent the entry of aid into the Gaza Strip... then we will resume our naval operations against the Israeli enemy," Abdulmalik al-Houthi said in a televised address.

Syria's leader Ahmed al-Sharaa has urged insurgents from ousted president Bashar al-Assad's Alawite minority to lay down their arms and surrender after the fiercest attacks on the war-torn country's new rulers yet.

A Syria war monitor reported on Saturday that more than 300 Alawite civilians have been killed in recent days by the security forces and their allies, as authorities clash with militants loyal to the former government of Bashar al-Assad.

Restoring security has been one of the most complex tasks for Syria's new authorities, installed after Islamist-led forces ousted Assad in a lightning offensive in December.

A high-level Hamas delegation arrived in Cairo to advance efforts on a fragile ceasefire in Gaza, which has largely paused hostilities with Israel, two senior Hamas officials told AFP Friday.

"The delegation will meet with Egyptian officials on Saturday to discuss the latest developments, assess progress in implementing the ceasefire agreement, and address matters related to launching the second phase of the deal," one official said.