JERUSALEM (AFP) - The number of anti-Israeli attacks fell in 2017, but US President Donald Trump's decision to recognise Jerusalem as Israel's capital has provoked greater instability, a security chief said Sunday (Dec 24).

"The level of terrorism has decreased this year with 54 attacks against 108 in 2016," said Nadav Argaman, head of the Shin Bet domestic security agency.

"The number of attacks thwarted has increased," he told a news conference.

But he said the situation had become "unstable... in Gaza and the occupied West Bank, after Trump's declaration".

Argaman said the calm prevailing before Trump's announcement on Dec 6 was "deceptive".

Islamist movement Hamas, which rules Gaza, "is trying with all its might to organise attacks in the West Bank to destabilise the Palestinian Authority," he said.

"In the coming period we will face many challenges, including calls and demonstrations in the streets launched by the Palestinian Authority" to protest against the US decision, said Argaman.

The Shin Bet chief said 400 bomb attacks were foiled in 2017, including 13 suicide bombings and nine kidnapping attempts, while 148 Hamas cells were dismantled in the West Bank.

Twelve Palestinians have been killed since Trump's decision, which sparked almost daily protests in the Palestinian territories and clashes with Israeli forces.