Iran has vowed to respond after a strike on its consulate building in Syria on Monday – which Israel was widely believed to be behind – killed 13 people, including a senior general.
The Israel Defense Forces (IDF) also announced it is halting all leave for soldiers serving with combat units.
It comes a day after reservists were called up to bolster air defence units.
Israeli authorities seem to believe an Iranian response is imminent and could come as soon as Friday, which is Quds Day – or Jerusalem Day – the last Friday in the Muslim Holy month of Ramadan.
It is a day which has frequently been used to stage pro-Palestinian and anti-Israel rallies, particularly in Iran.
On Thursday, GPS systems were being disrupted in central parts of Israel, a defensive measure designed to interfere with weapons which rely on it to set their location.
Israeli citizens reported being unable to use location-based app services in major cities like Tel Avid and Jerusalem far from active combat zones.
Monitoring website GPSJAM showed widespread interference with location signals across Israel.
A BBC producer said her GPS had located her in Cairo when she was in Jerusalem, and other users have shared similar accounts on social media.
IDF spokesman Rear Adm Daniel Hagari confirmed the country is using GPS blocking – which is sometimes referred to as “spoofing”.
Israelis have been urged to manually set their location on the app which issues alerts about incoming rocket attacks to ensure it remains accurate amid the GPS interference, the Times of Israel reported.
GPS is already disrupted in northern Israel, near the border with Lebanon, where Israel and the Iranian-backed group Hezbollah have exchanged fire almost daily for the last six months.
Separately, the IDF has urged people not to panic-buy. Writing on X, formerly Twitter, Rear Adm Hagari said: “There is no need to buy generators, store food and withdraw money from ATMs.
“As we have done until today, we will immediately update any change if it is in an official and orderly manner.”
Israel has not commented on the targeting of a building on Iran’s diplomatic compound in Damascus, the capital of Syria, but has been blamed by the country’s leader Ayatollah Ali Khamenei.
Iran’s President Ebrahim Raisi previously said the strike would “not go unanswered”, though it is unclear what actions Iran could take in response.
Among the 13 people killed in the strike were seven officers in Iran’s Revolutionary Guards, including senior general Mohammad Reza Zahedi and his deputy.
Zahedi is one of the most high-profile Iranian figures believed to have been killed by Israel in the country’s long campaign of targeted assassinations.
Israel has previously acknowledged carrying out strikes in Syria on targets it says are linked to Iran or its allied armed groups.