Palestinian medics said Muhammad Marus was killed when an Israeli helicopter fired a missile into a house in Bait Lahya in northern Gaza early on Wednesday.
Fighting erupted before dawn in the area as Israeli tanks thrust deeper into Bait Lahya as part of its latest military offensive against Palestinian fighters.
The Israeli army had no immediate comment on the strike.
In Hebron in the southern West Bank on Wednesday, senior Hamas official Imad al-Qawasma was arrested, Palestinian sources said.
Tel Aviv accused him of carrying out operations against Israel.
In Jalbun village east of Jenin, occupation forces demolished the house of Iyad Muhammed Abu al-Rab, leader of Islamic Jihad's military wing, al-Quds Brigades.
Abu al-Rab has been pursued by Israel for more than a year, Aljazeera's correspondent in Palestine said.
Israeli forces arrested five citizens, including four of his brothers, the correspondent added.
More than 93 Palestinians have been killed since Israel began its offensive a fortnight ago. Three Israelis and a Thai worker have also died.
Despite US and international pressure, Israeli Prime Minister Ariel Sharon last week ordered the army to intensify the assault in a bid to smash Palestinian fighters who fire rockets into Israel.
Resistance group Hamas has, however, vowed to continue launching rockets.