New Iranian Supreme Leader Mojtaba Khamenei issued his first comments, read out by a television presenter on Thursday, vowing to keep the Strait of Hormuz shut and calling on neighbouring countries to close US bases on their territory or risk Iran targeting them.
"I assure everyone that we will not neglect avenging the blood of your martyrs," the hardline cleric said.
It was not clear why he did not appear in person, but Iranian officials have said he was lightly wounded in initial strikes.
Israeli Prime Minister Benjamin Netanyahu held his first news conference since the US and Israeli air strikes on Iran started on February 28, issuing a veiled threat to kill Khamenei and defending the military assault.
"I will not detail the actions we are taking. We are creating the optimal conditions for toppling the regime but I won't deny that I can't tell you with all certainty that the people of Iran will topple the regime - a regime is toppled from the inside," Netanyahu said.
"But we can definitely help and we are helping."
US President Donald Trump weighed in on social media on Friday, saying the US was "totally destroying the terrorist regime of Iran".
"We have unparalleled firepower, unlimited ammunition, and plenty of time - Watch what happens to these deranged scumbags today," Trump said.
The Israel Defence Forces said on Friday its air force struck more than 200 targets in western and central Iran in the past day, including ballistic missile launchers, air defence systems and weapons production sites.
Overnight, Iran launched a barrage of missiles towards Israel, undermining earlier US and Israeli claims to have knocked out much of Iran's stock of long-range weapons.
Debris from a successful interception also caused minor damage to the facade of a building in central Dubai.
In Saudi Arabia, the defence ministry said two drones were intercepted in the east.
The prospect that one of the most severe disruptions ever to global energy supplies could endure sent oil prices up to $US100 a barrel on Thursday.
In an effort to stabilise global energy markets, the US issued a 30-day licence for countries to buy Russian oil and petroleum products stranded at sea.
Trump, who has already declared that the US and Israel won the war, said the US stood to make significant money from oil prices driven higher by the closure of the Strait of Hormuz, through which a fifth of global oil usually passes.
But stopping Iran having nuclear weapons was far more important than higher oil prices, he said on social media.
Trump's comments angered opposition Democrats, who accused the Republican president of caring too little about the war's impact on Americans and demanded more information about civilian casualties, particularly a strike that killed dozens of children at an Iranian girls' school.
Trump and his administration have given conflicting reasons for starting the war and have not provided an assessment of its expected cost or duration.
The death toll has risen to more than 2000 people, mostly in Iran, with almost 700 dying in Lebanon, where Israel has targeted central Beirut in an offensive against the Iran-backed Hezbollah group.
In Iraq, US Central Command said it was carrying out rescue efforts after one of its refuelling aircraft went down in an incident that involved another aircraft but was not the result of hostile or friendly fire.
Two tankers were set ablaze in the Iraqi port of Basra this week after being hit by suspected Iranian explosive-laden boats, and other ships have been struck in the Gulf near the Strait of Hormuz.
Drones have also regularly struck buildings and other infrastructure in Kuwait, Iraq, the United Arab Emirates, Bahrain and Oman.
Iran's strategy is to impose prolonged economic shock to force Trump to back off, with its military warning the world to prepare for oil prices of $US200 a barrel.
US Energy Secretary Chris Wright said he did not expect that to happen but did not rule it out.
