Dramatic video captured the moment a building in north Gaza was hit by an Israeli “roof knock” bomb — giving residents the chance to escape before the structure was destroyed in an airstrike.

The footage — shot by Fares Marwan Alghoul — shows the first impact by a device that produces a large cloud of dust and smoke as the one-story building remains standing.

The structure is then seen destroyed in a huge blast when a more destructive bomb or missile follows in the Tuesday incident, Storyful reported.

In 2009, the United Nations said the technique was “not effective as a warning and constitutes a form of attack against the civilians inhabiting the building.”

The Israel Defense Forces said it is one of several ways in which the military dedicates “resources to minimize civilian harm” in the enclave.

The military also has been calling residents by phone, sending them text messages and dropping flyers since its war on Gaza in 2008-2009.

During that campaign, the IDF said it had made 165,000 phone calls to residents instructing them to vacate immediately, often sending pre-recorded messages in Arabic, Agence France-Presse reported.

In its report, the UN said that in some cases, the strike occurred only five minutes after a phone call.

In the Jabaliya camp in the north of the Gaza Strip, Mohammed al-Ashqar said he had been warned to run out of his home.

“We received last night a call to evacuate the place, and when we did, the entire neighborhood was destroyed,” he told AFP. “My shop and house were completely destroyed.”

Amnesty International criticized the practice as not nearly enough to warn civilians.

“Giving warning does not absolve an attacking force from the obligation to adhere to other rules of international humanitarian law” including not targeting civilians, the rights group agency’s spokeswoman Sara Hashash told AFP.

“In many cases key elements of effective warning have been missing, including timelines, informing civilians where it is safe to flee, and providing safe passage and sufficient time to flee before an attack,” she added.

The IDF told The Post in statement that the military, “and the Air Force in particular, attach paramount importance to accuracy and reducing harm to civilians.

“When planning a target, the IDF devotes significant time and resources to preparing the attack and where feasible, uses various tools, including advance warnings, roof knocking, street knocking, target clearing operations and a variety of professional calculations carried out by the Operations Analysis Directorate,” it said.

“The use of these means varies depending on, among other factors, the type of target, the expected collateral damage, and the resources available at the time,” the IDF continued.

“Despite Hamas’ aims to endanger its own civilians, the IDF will continue to make efforts to minimize harm to civilians while continuing to attack Hamas terror targets,” it added.