Israel accused Iran of a “blatant violation” of their cease-fire deal just hours after it went into effect Tuesday — with the Jewish state immediately vowing to retaliate.

Israeli Defense Minister Israel Katz said he had ordered the military to resume strikes on the heart of Tehran in light of “Iran’s blatant violation” of the cease-fire that was only just declared by President Trump late Monday.

Iran’s military denied firing on Israel, according to state media — but sirens and explosions sounded across northern Israel throughout the morning.

Hours earlier, Trump had posted on Truth Social: “THE CEASEFIRE IS NOW IN EFFECT. PLEASE DO NOT VIOLATE IT!”

Just before it started, Iran launched a final onslaught of roughly 20 missiles at Israel that killed at least four people in the early hours of Tuesday.

The missiles damaged at least three densely packed residential buildings in the city of Beersheba, injuring at least 20 people, Israel’s military said.

First responders said they’d retrieved four bodies from one building and were scouring the debris for more.

“Sirens sounding in Israel due to a missile launch from Iran,” the IDF said in a slew of early X posts, adding that its navy had intercepted more than 15 drones launched by Iran overnight.

“For the third time in the last hour, Israelis are currently running to shelter due to another missile launch from Iran.”

Israel, for its part, launched a blitz of airstrikes targeting sites across the Islamic Republic before dawn.

It then detected another Iranian barrage hours after the cease-fire was supposed to have started.

Trump had blasted out news of the agreement on Truth Social Monday evening: “CONGRATULATIONS TO EVERYONE! It has been fully agreed by and between Israel and Iran that there will be a Complete and Total CEASEFIRE (in approximately 6 hours from now, when Israel and Iran have wound down and completed their in progress, final missions!), for 12 hours, at which point the War will be considered, ENDED!”

“Officially, Iran will start the CEASEFIRE and, upon the 12th Hour, Israel will start the CEASEFIRE and, upon the 24th Hour, an Official END to THE 12 DAY WAR will be saluted by the World. During each CEASEFIRE, the other side will remain PEACEFUL and RESPECTFUL.”

In accepting the cease-fire, Israeli Prime Minister Benjamin Netanyahu said his country had achieved its goals of destroying Iran’s nuclear program and missile capabilities after launching its June 13 surprise attack.

“Israel thanks President Trump and the United States for their support in defense and their participation in eliminating the Iranian nuclear threat,” Netanyahu had said.

Meanwhile, Iran’s top security body, the Supreme National Security Council, said its military had forced Israel to “unilaterally accept defeat and accept a ceasefire” but that its forces would “keep their hands on the trigger” to respond to “any act of aggression by the enemy.”

Iranian Foreign Minister Abbas Araqchi said Iran would halt its retaliatory strikes provided that Israel stopped attacking as of 4 a.m. in Tehran.

The shaky cease-fire came after a day of hostilities spread further across the region when Iran launched a limited missile attack on a US military base in Qatar in retaliation for the earlier American bombing of its nuclear sites.

With Post wires