There were no visible signs of panic in Israel on Friday as shoppers in Jerusalem went to get groceries and families enjoyed a sunny afternoon on cafe terraces before they closed for the Sabbath.
Israel’s foreign ministry did not comment on reports that some Israeli diplomatic missions had been partially evacuated and security stepped up.
An Iranian attack on Israel in some form has been threatened by the country’s Supreme Leader Ali Khamenei since the Damascus strike on April 1, which killed a senior Iranian Revolutionary Guards commander, Gen Mohammad Reza Zahedi and six other members of the group.
Israel has not claimed the air strike but is widely believed to have been responsible.
Mr Khamenei said on Wednesday: “When they attacked our consulate area, it was like they attacked our territory. The evil regime must be punished, and it will be punished.”
It is unclear whether Iran’s response would come in the form of missiles from Iranian soil or from its nearby proxies in Lebanon and Syria.
Western intelligence officials are expecting attacks on military and government buildings in Israel, but do not think civilians will be targeted.
“I can’t speak to what the intelligence picture tells us in terms of the size, scale, scope of what that attack might look like, except to say that we’re taking this seriously,” Mr Kirby said, adding that the threat was “credible”.
“The revenge will come,” wrote Israel’s largest daily newspaper, Yedioth Ahronoth. “For the moment, the premise is that it will be very soon, in the next few days.”
Given its magnitude, a strike on military targets would be challenging for Israel to defend itself against, US officials told CBS News.
The officials said they hoped Iran would opt for a smaller-scale strike.
Other unnamed US officials told The Wall Street Journal that Israel was preparing for a direct attack from Iran on the north and south of the country as early as Friday or Saturday.
On Friday, Hezbollah, the Iran-aligned militia in Lebanon, launched around 40 missiles into Israel in retaliation for its latest bombardment of villages in Gaza.
The attack was partially intercepted by the Iron Dome defence system.