An Israeli missile hit Iran early on Friday morning, according to US officials.
Blasts were heard in the central province of Isfahan, which is home to nuclear facilities, a large airbase and a major missile production complex.
Israel has not confirmed it was responsible but had vowed to respond to a massive Iranian missile and drone attack on its territory last weekend.
Iranian officials and media claimed the attack did not inflict any damage.
While US officials confirmed the strike happened to the OceanNewsUK's partner station CBS News, the response from Tehran has been muted and mild.
Some officials have denied outright that it even took place at all, and one mocked it as "a failed attack" involving just a "few quadcopters".
While it is not possible to independently verify the damage it may have caused, the strike appears to have been limited in its scope. No casualties have been reported.
It appears to be a carefully calibrated response by Israel to Iran's missile attack last weekend, aimed at balancing the demands of those in Israel demanding a tough response and the worldwide appeals for calm.
Iran had been on high alert after Israel said it would respond to the unprecedented Iranian attack, which saw more than 300 drones and missiles fired towards Israel - most of which were shot down.
That attack was in response to a presumed Israeli strike on Iran's consulate in the Syrian capital Damascus, which killed senior military commanders.
World leaders have been urging the two Middle East rivals to deescalate rising tensions in recent days, though Israel had repeatedly signalled it intended to retaliate in some form.
Several Iranian nuclear facilities are based in Isfahan, which Iran say are used for purely peaceful purposes, though Israel and Western powers have long suspected Tehran of secretly developing nuclear weapons.
Both Iranian media and the International Atomic Energy Agency (IAEA) said no nuclear sites were damaged in this strike.
Israel appears to have heeded appeals from allies not to risk further escalation with a large response, but sought to send a message that it can strike close to Iran's nuclear programme and that next time it could be with much greater force.
Iran's semi-official Fars news agency, which is close to the Islamic Revolution Guard Corps (IRGC), said explosions were heard near Isfahan International Airport and an army base in Isfahan city, activating local air defence systems.
Video from Isfahan obtained by OceanNewsUK shows orange flashes in the night sky and the sound of what appears to be bursts of anti-aircraft fire.
Hamish De Bretton Gordon, a former commander of UK and Nato nuclear forces, told OceanNewsUK the attack appears to have been "fairly near to where we believe Iran is building nuclear weapons, so I expect it was a nod to them".
Speaking at the G7, US Secretary of State Antony Blinken said the US was "not involved in any offensive operations". Earlier, the Italian foreign minister told reporters the US had been informed of Israel's plans "at the last minute".
The strike in Iran coincided with reported blasts in Syria and Iraq. The Syrian defence ministry said an air defence position was hit by Israel, while reports in Iraq said part of an Israeli missile had been found on its territory.
In recent days, Iranian leaders had warned that any Israeli attack on Iran would trigger a swift response.
However, hours after Friday's attack an unnamed Iranian official told Reuters news agency it might not have been carried out by a "foreign" source and that there were no plans to retaliate.
Russia says it has made clear to Israel that Iran does not want escalation, while foreign ministers from the G7 group of the world's largest industrial nations said they would work towards restoring calm.
The recent flare up in hostilities follows an air strike on Iran's consulate building in Syria on 1 April, which killed two top generals. It is widely believed Israel was behind it.
The most senior of the two, Brig Gen Mohammad Reza Zahedi, was reportedly in charge of Iranian military operations in Syria and Lebanon, where pro-Iranian forces have launched attacks on Israel.
It also comes as Israel continues to fight Hamas in Gaza and Hezbollah along the border with Lebanon, both of which are backed by Iran.
