The strike hit an apartment building in Gaza City's Nasr neighbourhood at dawn, with medics confirming the death of Al-Beik. Another person died from wounds sustained in the attack, health officials said.
Israeli Prime Minister Benjamin Netanyahu and Defence Minister Israel Katz said the military had targeted Al-Beik, accusing him of planning attacks and recruiting militants. Hamas issued a statement confirming his death.
The killing comes amid heightened tensions over the ceasefire that took effect in October. Israel says Hamas has been rearming and launching attacks in violation of the agreement and has stepped up strikes in recent weeks. The military said it has killed at least 20 Hamas figures this month, including senior commanders and people it identified as involved in the October 7, 2023 attacks or who held Israeli hostages.
Hamas has denied trying to carry out attacks or rebuild its arsenal, and accuses Israel of undermining the Gaza deal. The ceasefire, brokered by the United States, called for the eventual reconstruction of the territory, but little progress has been made amid disagreements over terms for Hamas to disarm and Israel to withdraw its troops.
Casualty figures from both sides remain contested. At least 1,400 Palestinians have been killed in Gaza since the ceasefire took effect, according to the territory's health officials, while the Israeli military reports four soldiers killed. Palestinian authorities say more than 73,000 people have been killed in Israel's broader assault on Gaza, which began after Hamas-led fighters killed about 1,200 people in southern Israel in October 2023.