A second mortar shell fired from Syria struck the Golan Heights on Saturday evening, Channel 2 News reported, hours after a shell that exploded in the area led to retaliatory Israeli strikes.
The shell exploded on the border, causing no casualties or damage. It was the fourth such incident this week.
Earlier a mortar shell had exploded inside Israeli territory. It too did not cause harm. A military spokeswoman said the projectile was most likely unintentional “spillover” from the internal fighting in Syria.
Israeli aircraft struck Syrian army positions on Saturday after fire from its war-torn neighbour hit the Israeli-held zone of the Golan Heights earlier in the day, the military said.
The Israeli strike targeted artillery positions of the Syrian regime in response to "a projectile" which hit the northern Golan, causing no injuries or damages, an army statement said.
"The Syrian government (is) accountable for this blatant breach of Israeli sovereignty, the IDF (Israel defence forces) will continue to act in order to safeguard Israel and its civilians," it added.
A military spokeswoman said the projectile was most likely unintentional "spillover" from the internal fighting in Syria.
It was the third such incident in six days, and came soon after Russia and the United States announced a deal on a new Syrian ceasefire, set to come into force on Monday.
There were similar events in July and previously.
Israel has sought to avoid being drawn into Syria's complex war which is now in its sixth year, but it has attacked Syrian military targets when fire from the conflict spills over.
Israel seized 1,200 square kilometres (460 square miles) of the Golan Heights from Syria in the Six-Day War of 1967 and later annexed it in a move never recognised by the international community.