US President Donald Trump has threatened that "all hell would rain down on" Iran if it did not make a deal, an ultimatum that Tehran has rejected.
Senior Iranian military officer, Gen Ali Abdollahi Aliabadi, echoed Trump's rhetoric, saying "the gates of hell will open for you".
On Saturday Iran fired more missiles at the Gulf States, Iraq and Israel, with falling debris from intercepted missiles causing damage. Since then, more strikes have been reported in Israel, Bahrain, Kuwait and the UAE overnight.
The threats from the US and Iran came as both searched for a missing American crew member after a US F-15 fighter jet was shot down over Iran on Friday. The pilot was rescued, US media says.
Iranian state media reported that at least four people were killed in a US-Israeli airstrike in the same region being searched for the missing US weapon systems officer.
Missile strikes hit telecommunications towers in the city of Dehdasht, Tasnim news agency, which is linked to the Islamic Revolutionary Guards Corps, reported.
Unverified videos on social media show hundreds of people heading to a mountainous area in south-western Iran to search for the missing American. Iranian officials have been urging citizens to help find the missing crew member "alive" and are offering bounties for their capture.
A US A-10 Warthog aircraft that was part of an initial search-and-rescue mission for the downed jet was also shot and damaged, but its pilot was rescued after they ejected over the Gulf.
Also on Saturday, Trump reiterated his threat that he would resume attacks on Iranian energy plants after a 10 day pause for Tehran to "make a deal".
On Truth Social he said "all Hell will reign down on them" if Iran failed to do so, or to reopen the Strait of Hormuz, within 48 hours.
Iran waved off the threats and rejected Trump's demand.
Gen Aliabadi, of Iran's central military command, said Trump's threat was a "helpless, nervous, unbalanced and stupid action".
Ebrahim Zolfaghari, a spokesperson for Khatam al-Anbiya Central Headquarters, added: "If hostility escalates, the entire region will turn into hell for you; the illusion of defeating the Islamic Republic of Iran will become a quagmire into which you will sink."
The US and Israel continued their bombardment of Iranian military, energy and other industrial sites on Saturday.
Kuwait said an Iranian drone attack knocked out two power generation stations and hit water desalination plants.
Earlier attacks caused significant damage to a government office complex and a fire at the Kuwaiti oil ministry.
Meanwhile Israel said it had intercepted missiles launched from Iran.
On Saturday Trump shared a video on his Truth Social platform which he said showed a "massive strike" on the capital Tehran. However, the video appeared to be 24 hours old.
Trump claimed in his post that "many of Iran's Military Leaders, who have led them poorly and unwisely, are terminated, along with much else", following the strike.
There has been no response from Tehran, and no further details from the US.
A major petrochemical hub in south-western Iran was struck, state media reported.
Five people were killed and 170 were injured in the attack on the Mahshahr facility, it reported.
Iran also said the area around its Bushehr nuclear power plant had been attacked for the fourth time during the war.
One of the plant's employees was killed in the attack, Iran's Atomic Energy Organisation said. It blamed the US and Israel for the attack, but neither country has confirmed carrying it out.
The International Atomic Energy Agency - the UN's nuclear watchdog - said no increase in radiation levels has been reported.
Iran's nuclear programme has long been a point of contention, leading to extensive international sanctions. The US-Israeli war with Iran began on 28 February, two days after a third round of indirect US-Iran nuclear talks in Geneva.
DW Russian 
