By Alex Marquardt, Helen Regan, Hamdi Alkhshali, Artemis Moshtaghian and Adam Pourahmadi, CNN

(CNN) — Israel has carried out a military strike inside Iran, a US official told CNN Friday, a potentially dangerous escalation in a fast widening Middle East conflict that Iranian government officials have so far sought to play down.

The United States was given advance notification Thursday of an intended Israeli strike in the coming days, but did not endorse the response, a second senior US official said. Secretary of State Antony Blinken later confirmed the US “has not been involved in any offensive operations,” but was focusing on Israel’s defense and de-escalation.

Iran’s air defense systems were activated in the cities of Isfahan and Tabriz after three explosions were heard close to a major military airbase near Isfahan, state media reported early Friday morning.

Maj. Gen. Abdolrahim Mousavi, the commander-in-chief of Iran’s army, said the explosions in the sky above Isfahan were related to anti-aircraft systems shooting at what he called a suspicious object, which did not cause any damage, Iranian state news IRNA reported. Other Iranian officials said air defenses intercepted three drones and there were no reports of a missile attack.

Iran has not identified the source of the strike.

Multiple state-aligned news agencies reported that sites associated with Iran’s nuclear program were secure and the attack appeared to be limited in scope.

Iranian media appeared to further minimize the scale of the attack on Friday, broadcasting calm scenes from Isfahanshowing residents walking through parks and visiting landmarks. Traffic was reported as normal and the airport was also reported to have reopened after flights were briefly canceled or suspended early Friday.

Reports of Friday’s strike came hours after Iran’s Foreign Minister Hossein Amir-Abdollahian told CNN that if Israel takes any further military action against Iran, its response would be “immediate and at a maximum level.”

“If the Israeli regime commits the grave error once again our response will be decisive, definitive and regretful for them,” he added, noting that this warning had been communicated to the White House via the Swiss Embassy in Tehran.

Tensions across the Middle East remain on a knife edge, following Iran’s unprecedented direct strike against Israel late Saturday. The attack, during which Iran launched more than 300 drones and cruise missiles toward Israel, came in response to a suspected Israeli strike on an Iranian diplomatic complex in the Syrian capital, Damascus, on 1 April, which killed a top commander, and several others.

Separately, “material losses” were reported in southern Syria after an Israeli strike, targeted “our air defense sites in the southern region,” Syrian state media SANA reported Friday citing a military source. The Israeli military said that it does not comment on reports in foreign media.

The Israeli military said it was unable to provide a comment on Friday, when asked by CNN about reports of explosions in Iran.

At the end of a three-day meeting in Capri, Italy, the Group of Seven (G7) nations urged all parties in the region to “prevent further escalation.” Jordan’s Foreign Minister Ayman Safadi also warned the strikes risk “dragging the region into further conflict,” adding that the “Israeli-Iranian retaliations must end.”

Iran warned of ‘maximum’ response hours earlier

Israel’s action in Iran is the latest escalatory move in a region that has been rocked by Israel’s devastating war in Gaza following Hamas’ brutal October 7 attack. That attack killed more than 1,200 people, mostly civilians, and saw more than 200 others taken hostage.

Israel’s bombardment and siege of Gaza has killed more than 33,000 Palestinians, according to Palestinian officials, caused widespread destruction of the enclave and sparked a humanitarian crisis where more than 1 million people face ‘catastrophic’ levels of hunger.

Prior to Friday’s Israeli strike, the US expectation was the country would not target Iran’s civilian or nuclear facilities, the senior US official told CNN.

CNN has previously reported that Israel told the US its response to the weekend attacks would be limited in scope. US intelligence had suggested Israel was weighing a narrow and limited strike inside Iran because they feel like they have to respond with a kinetic action of some kind given the unprecedented scale of the Iranian attack

The range of targets was “never specified in precise terms but nuclear and civilian locations were clearly not in that category,” the senior official added.

Calls for restraint

Israel’s Western allies have both rallied to its defense in the wake of Iran’s attack Saturday, while also urging restraint.

US President Joe Biden told Israeli Prime Minister Benjamin Netanyahu he should consider Iran’s strikes a win, since they had been largely unsuccessful and demonstrated Israel’s ability to defend itself.

Biden had already made clear to Netanyahu that the US would not participate in any offensive operations against Iran in response, a senior administration previously told CNN.

Benny Gantz, a key member of Israel’s war cabinet, had pushed for a swift response to the attack, two Israeli officials told CNN, arguing that the longer Israeli delayed its response, the harder it would be to garner international support for it.

Some hardline officials have gone further. Israeli National Security Minister Itamar Ben Gvir said Israel should “go crazy” in response. Ben Gvir appeared to criticize Israel’s reported strike, publishing a one-word response on X early Friday morning – a slang word meaning “lame” or “weak.”

Israel’s opposition leader Yair Lapid called Ben Gvir’s comment “unforgivable.”

“Never before has a minister in the security cabinet done such heavy damage to the country’s security, its image and its international status,” Lapid said.

Jasmine El-Gamal, a former Middle East adviser to the US Defense Department, told CNN that Israel and Iran’s tit-for-tat strikes were about “posturing and messaging.”

“Neither side, obviously, is willing or ready to escalate into an all-out war. The Israelis in particular cannot get into an all-out war without the full support, both military and political, of the Americans, which President Biden made it clear he was not willing to give,” she said.

El-Gamal said Israel’s reported strike was meant to tell Iran, “We can get to your nuclear sites if we want to. We know where they are, and even though we didn’t hit them this time – we can do it.”