Washington: Amid fears of the ongoing hostilities in Gaza devolving into a larger Middle-Eastern conflict, US President Joe Biden on Friday said he expects Iran to attack Israel 'sooner than later', CNN reported.

"I don't want to get into secure information but my expectation is sooner than later," Biden told reporters when asked how imminent an Iranian attack on Israel would be.

As has been reported globally, Tehran vowed revenge after Israel launched airstrikes on the Iranian embassy in the Syrian capital, Damascus, taking out three top military generals.

On his message to Iran at this time, the US President said, "Don't."

In response to more shouted questions from reporters in the White House, asking if American troops were at risk, Biden returned to the podium saying that the United States was 'devoted' to the defence of Israel, CNN reported.

"We are devoted to the defence of Israel. We will support Israel we will help defend Israel and Iran will not succeed," Biden said.

The US has been on high alert for a significant Iranian retaliatory attack on Israel in recent days, as fears grow of a wider regional war.

There remains a "real, credible and viable" threat of Iran launching strikes, the White House said on Friday, following Israel's attack on an Iranian diplomatic compound in Syria last week, killing three Iranian generals.

Biden, who warned this week that Iran was threatening a 'significant attack' on Israel, has been receiving constant updates on the situation from his national security team.

The US and several other countries, including India, Britain and France, issued new travel guidelines for government employees in Israel as the Iranian threat loomed.

"In view of the prevailing situation in the region, all Indians are advised not to travel to Iran or Israel till further notice. All those who are currently residing in Iran or Israel are requested to get in touch with Indian Embassies there and register themselves," the Ministry of External Affairs stated in an official release.

"We're watching this very, very closely," said John Kirby, the US National Security Council spokesman, who declined to provide information about the expected timing of the threat.

The US will attempt to intercept any weapons launched towards Israel, if it's feasible to do so, two officials in Washington told CNN, an indication of the level of ongoing cooperation between the two militaries.

US Navy personnel in the Red Sea previously intercepted long-range missiles launched from the Houthis in Yemen towards Israel. US forces in Iraq and Syria could also potentially intercept drones and rockets targeting northern Israel, depending on the location from which they're launched, CNN reported.

The US Defence Department was also moving additional assets to the Middle East "to bolster regional deterrence efforts and increase force protection for US forces", a US defence official told CNN, as Israel and the US braced for a potential Iranian attack.

The Pentagon has been working specifically to bolster air defences for the US troops stationed in Iraq and Syria, who came under attack by Iran-backed proxy forces over 100 times between October and February, CNN reported.

In January, three US servicemembers were killed when a drone got through US air defences at the Tower 22 base in Jordan.

The US is not anticipating that Iran or its proxies will attack US forces as part of its retaliation but is moving assets just in case.

"It would be imprudent if we didn't take a look at our posture in the region to make sure that we're properly prepared," Kirby said.

CNN reported last week that the US was on high alert and actively preparing for an attack by Iran targeting Israeli or American assets in the region. Officials said such an attack could come within the week.

This report is auto-generated from a syndicated feed