The dawn strike came hours after senior Druze clerics and armed factions reaffirmed their loyalty to Damascus and rejected any call for secession.

They also urged the authorities to appoint local officials to government posts in the Druze heartland in Sweida province.

The statement followed sectarian clashes between Druze fighters and Syrian forces, including government-affiliated groups.

More than 100 people were killed in Jaramana and Sahnaya near Damascus and in Sweida, war monitor the Syrian Observatory for Human Rights said.

Friday's explosion from the presidential palace area was heard across Damascus, an AFP correspondent reported.

Israeli military spokesman Avichay Adraee said "warplanes attacked... the area near Ahmed Hussein al-Sharaa's palace in Damascus", referring to the interim president.

In a joint statement, Israeli Prime Minister Benjamin Netanyahu and Defence Minister Israel Katz called it a "clear message" to Syria's new rulers.

"We will not allow forces to be sent south of Damascus or any threat to the Druze community," they said.

Syria's presidency called the strike "a dangerous escalation against state institutions", and accused Israel of destabilising the country.

UN Secretary-General Antonio Guterres condemned the Israeli strike as a violation of Syria's sovereignty, which he said Israel must respect along with "its unity, its territorial integrity and its independence", his spokesman said.

After this week's sectarian clashes a de-escalation deal was agreed between Druze representatives and the government, prompting troop deployments in Sahnaya and tighter security around Jaramana.

Syrian officials said the agreement also included the immediate surrender of heavy weapons.

An AFP photographer saw troops taking over checkpoints from Druze gunmen in Jaramana, although no handover of weapons was witnessed.

- 'Outlaw groups' -

Qatar, a main backer of Syria's new rulers, called Friday's Israeli air strike "blatant aggression against the sovereignty" of the country.

A German foreign ministry statement said "Syria must not become the venue for regional tensions to be played out".

A 55-year-old who asked to be identified only as Ahmed said Friday's blast woke his family.

"Unfortunately, we have gotten used to explosions and Israeli strikes in Damascus. Curse them," he said.

Israel has attacked hundreds of military sites since Islamist-led forces deposed longtime president Bashar al-Assad in December.

It has also sent troops into the demilitarised buffer zone that used to separate Israeli and Syrian forces on the Golan Heights.

On Wednesday, Israel launched strikes near Damascus and threatened more if violence against the Druze continued.

The unrest inside Syria was sparked by the circulation of an audio recording attributed to a Druze citizen and deemed blasphemous. AFP was unable to confirm its authenticity.

Syria's government said "outlaw groups" were behind the violence, but the Observatory and Druze residents said forces affiliated with the new authorities attacked Jaramana and Sahnaya and clashed with Druze gunmen.

"The situation is calm, but we are scared. Everyone is terrified," 35-year-old housewife Arij told AFP, adding that many Christians and Druze "have fled to Damascus".

- 'Genocidal campaign' -

Mohamad Halawa, a security official in Damascus province, said there was now a security cordon around Jaramana where residents would be "under the umbrella of the state and the judiciary".

In Sweida, religious authorities and military factions said after a meeting that they are "an inseparable part of the united Syrian homeland", and rejected "division, separation or secession".

State news agency SANA reported that security forces were being sent to Sweida to "maintain security".

The move came after Sheikh Hikmat al-Hijri, a Druze spiritual leader, on Thursday condemned what he called a "genocidal campaign" against his people.

Syria's new Islamist authorities have roots in the Al-Qaeda jihadist network. They have vowed inclusive rule in the multi-confessional, multi-ethnic country, but must also contend with pressures from radical Islamists within their own ranks.

The latest violence follows massacres of Alawites in March, when the Observatory said the security forces and their allies killed more than 1,700 civilians.

It was the worst bloodshed since the overthrow of Assad, who is from the minority community.

The government accused Assad loyalists of sparking the violence, and has begun an inquiry.