The US defence secretary held talks in Israel as flaring violence killed three suspected Palestinian militants in the Israeli-occupied West Bank and protesters rallied against Prime Minister Benjamin Netanyahu's hard-right government.

Late Thursday, a gunman shot and wounded three people on a Tel Aviv street in what police said could be a "terrorist attack".

Austin said, in a joint news conference with Israeli Defence Minister Yoav Galant, that the US commitment to Israel's security was "iron-clad".

But the US remained "firmly opposed to any acts that could trigger more insecurity, including settlement expansion and inflammatory rhetoric," he said, adding: "We are especially disturbed by violence by settlers against Palestinians."

Thousands of Israelis opposed to the Netanyahu government's legal reform plans had blocked roads in and around Ben Gurion airport, near Tel Aviv, forcing a last-minute change of venue for Austin's talks.

Just hours before his arrival, undercover agents of Israel's border police shot dead three suspected Palestinian militants in the West Bank.

The Palestinian health ministry announced the "martyrdom" of three men shot by Israeli forces in Jaba, near the northern city of Jenin.

And hours after his press conference with Galant, the shooting occurred on a popular street in the centre of Tel Aviv, leaving one of the wounded in a critical condition, according to emergency services.

National Security Minister Itamar Ben-Gvir said a police officer "eliminated the heinous terrorist and saved many lives".

Austin had reported "a very frank and candid discussion among friends about the need to de-escalate, to lower tensions and restore calm especially before the holidays of Passover and Ramadan".

He also called on the "Palestinian leadership to combat terrorism and to resume security cooperation and to condemn incitement".

- Iran concerns -

In their meetings with Austin, Netanyahu and his defence minister raised Israeli concerns that its arch-foe Iran is developing nuclear weapons, something the Islamic republic has always denied.

"It is our duty to take all measures necessary to prevent Iran from gaining nuclear weapons," Galant told reporters.

Austin said "diplomacy is the best way to prevent Iran from getting a nuclear weapon", while adding the US would not allow that to happen.

Their talks came ahead of Netanyahu's departure for Rome, which protesters had sought to obstruct using their vehicles to block access roads.

Nine straight weeks of protests have been held by opponents of the reform plans, which would give politicians greater power over the courts. They have drawn tens of thousands of demonstrators who regard the proposals as a threat to democracy -- a view shared by the country's President Isaac Herzog.

In a solemn television address, Herzog said the legislation under discussion "should disappear" quickly because it "threatens our democratic foundations".

Austin touched on the Israeli dispute by recalling the importance of democracy being built on "strong institutions... and on an independent judiciary".

The mounting violence in the West Bank has coincided with the tenure of Netanyahu's coalition government, which took office in December and is regarded as the most right-wing in Israeli history.

The government of Netanyahu, who is on trial for corruption, has vowed to continue the expansion of West Bank settlements considered illegal under international law.

In the morning, the Palestinian health ministry announced the "martyrdom" of three men shot by Israeli forces in Jaba, near the northern city of Jenin.

- 'Shots were fired' -

Israeli police, who identified two of the men as operatives of militant group Islamic Jihad, said special forces accompanied by soldiers had been in Jaba to arrest suspects involved in shooting attacks against soldiers. It said the pair

"During the operation, shots were fired at the border police undercover officers from the wanted men's car. Border police undercover officers responded with fire, and killed the three armed men in the car," police said, adding the third man was also a suspected militant.

Islamic Jihad condemned Israel for the "heinous assassination" in Jaba.

A Tuesday raid by the Israeli military in Jenin left seven Palestinians dead, including a member of Hamas accused of killing two Israeli settlers last month.

The Palestinian health ministry identified the seventh fatality from Tuesday's raid as Walid Nassar, 14.

Since the start of the year, the Israeli-Palestinian conflict has claimed the lives of at least 75 Palestinian adults and children, including militants and civilians.

Twelve Israeli civilians, including three children, and one policeman, as well as one Ukrainian civilian have been killed over the same period, according to an AFP tally based on official sources from both sides.