Lebanese Prime Minister Saad Hariri said two Israeli drones which crashed in a suburb of Beirut dominated by the Iranian-backed Hezbollah were designed to stir up regional tensions.
In the first such incident in more than a decade, one drone fell and second exploded before dawn near the ground and caused some damage to Hezbollah's media center in the southern Dahiyeh suburbs, Reuters quoted a Hezbollah official as saying.
"The new aggression...constitutes a threat to regional stability and an attempt to push the situation towards further tension," Hariri said in a statement from his office.
The Israeli military declined to comment.
The early morning incident in south Beirut came hours after Israel said it had conducted airstrikes in neighboring Syria to prevent an Iranian force from launching an attack on Israel.
A war monitor said the air raids in the southeast of Damascus killed two Hezbollah members and one Iranian among five fighters.
The Shiite movement and Israel have upped their belligerent rhetoric in recent months, after fighting several wars the last of which was in 2006.
Lebanon's army said "two drones belonging to the Israeli enemy violated Lebanese airspace... over the southern suburbs of Beirut", a Hezbollah stronghold in the capital.
"The first fell while the second exploded in the air causing material damage," he said.
Earlier a Hezbollah spokesman, Mohamed Afif, insisted his movement did not shoot down either of the two drones but said that one had damaged a Hezbollah media center.
"The first drone fell without causing damage while the second one was laden with explosives and exploded causing huge damage to the media center," Afif said.
"The first drone did not explode and it is now in the possession of Hezbollah which is analyzing it."
- 'Threat to regional stability' -
An AFP correspondent saw security forces deployed in the area of the incident.
Lebanon's President Michel Aoun said the drone incursion targeted "stability and peace in Lebanon and the region".
Hariri condemned a "blatant attack on Lebanon's sovereignty".
Hariri also charged that it was in violation of UN Security Council Resolution 1701 that ended the 2006 war between Israel and Lebanon's Hezbollah.
The Lebanese Foreign Ministry counted 481 Israeli violations of Lebanese airspace in the past two months and instructed Lebanon's representative to the UN to submit an immediate complaint.
Israeli military spokesman Jonathan Conricus said the Israeli attack struck in Aqraba, southeast of Damascus, and targeted "terror targets and military facilities belonging to the Quds force (of Iran's elite Revolutionary Guards) as well as Shiite militias".
The Syrian Observatory for Human Rights, a Britain-based monitor, said the attack had killed two Hezbollah members, an Iranian and two fighters.
But a high-ranking official in Tehran denied Iranian positions had been hit.
"This is a lie and it is not true," Mohsen Rezaie, the secretary of the Expediency Council, told ILNA news agency
A Syrian military source quoted by the state news agency said: "At 2330 (2030 GMT), anti-aircraft defenses detected enemy targets from Golan heading towards the area around Damascus".
"The aggression was immediately confronted and so far the majority of the enemy Israeli missiles have been destroyed before reaching their targets."
In a statement issued just minutes after the army announced its attack, Netanyahu hailed what he termed a "major operational effort" in thwarting an attack.
"Iran has no immunity anywhere," Netanyahu said. "Our forces operate in every sector against the Iranian aggression."
Conricus said while Iranian forces had launched rockets and missiles at Israel from Syria three times during 2018, the use of "kamikaze" attack drones was a new and "different tactic".
Israel insists it has the right to target positions held by Iran and its ally Hezbollah out of self-defense.