Israel's Iron Dome missile defence system destroyed a rocket fired from Syria at the Israeli-held zone of the Golan Heights Saturday in an apparent uptick in tension between the uneasy neighbours.

"A projectile fired from Syria was intercepted by the Iron Dome aerial defence system. No injuries have been reported," a military statement said.

A spokeswoman could not immediately say if it was the first time Iron Dome had seen action on the Golan, but it was a departure from recent tit-for-tat artillery fire and occasional retaliatory air strikes.

Israeli public radio said the military believed that the Syrian fire was an unintentional spillover from the country's complex civil war which is now in its sixth year.

Israel has sought to avoid being drawn in, but has attacked Syrian military targets when fire fell on its side of the divide.

On Tuesday, Israeli aircraft targeted Syrian army positions after what the military said was probably stray fire hit the Israeli-occupied zone.

Syria said it had shot down an Israeli warplane and a drone, a claim denied by Israel.

The increased tension comes after a new Syrian ceasefire brokered by Russia and the United States came into force on Monday.

The truce does not apply to areas held by militants such as the Islamic State group.

The Israeli army holds the Syrian government accountable for any fire from its territory, regardless of the source.

Israel seized 1,200 square kilometres (460 square miles) of the Golan from Syria in the Six-Day War of 1967 and later annexed it in a move never recognised by the international community.