"Our people will not surrender, and the resistance will continue to defend our rights in the face of this criminal enemy," Haniyeh said in a statement after the Hamas-run government media office reported 210 people killed in Nuseirat camp.
Israeli forces said they rescued four hostages alive from the Gaza camp. Noa Argamani, 26, Almog Meir Jan, 22, Andrey Kozlov, 27, and Shlomi Ziv, 41, had been rescued from two separate buildings "in the heart of Nuseirat" in a "complex daytime operation", the military said, adding they were in "good medical condition".
They were among 251 captives seized by the militants in their October attack on southern Israel. There are now 116 hostages remaining in Gaza, including 41 the army says are dead.
Footage posted on social media showed Argamani emotionally reuniting with her father after her rescue, as well as beachgoers erupting into cheers in Tel Aviv when a lifeguard announced the four had been freed.
Campaign group the Hostages and Missing Families Forum, which has pressed Israel's government to reach a deal that would free the captives, hailed the rescue as a "miraculous triumph".
Israeli Defence Minister Yoav Gallant said on X: "Noa, Almog, Andrey and Shlomi -- we are overjoyed to have you home."
"The message this morning to Hamas is clear: we are determined to bring back home all the hostages," army spokesman Rear Admiral Daniel Hagari said.