Two Palestinians were killed in an Israeli raid on the outskirts of Nablus in the northern West Bank, where clashes had erupted, the Palestinian Health Ministry said.
A military spokesman said gunmen exchanged fire with Israeli forces.
Earlier the military said aircraft struck Islamic Jihad command centres and rocket launchers in pre-dawn operations in Gaza.
Grainy black and white aerial footage it released showed explosions and clouds of smoke rising from bombed sites.
A few hours later Gaza militants fired rockets, setting off sirens and sending Israelis in border communities running to bomb shelters.
There were no reports of casualties inside Israel.
Egypt has been trying to mediate a truce to the latest outbreak of violence, which has so far killed at least 33 Palestinians and one Israeli.
More than 140 Palestinians and at least 19 Israelis and foreigners have died in clashes since January.
A Palestinian official familiar with the truce talks described them as "complicated" and "tough" but confirmed that Cairo was pressing ahead with its efforts.
Six top Islamic Jihad commanders have been killed since Tuesday, when Israeli forces launched a campaign against the group, which it said was planning attacks.
Islamic Jihad, the largest armed group in Gaza after the ruling Islamist Hamas, has since fired more than a thousand rockets, some deep into Israel.
One woman was killed on Thursday when an apartment was struck in a Tel Aviv suburb.
At least four women and six children have died in densely populated Gaza, an impoverished coastal territory blockaded by Israel and Egypt since 2007.
Israel says four Palestinians were killed by misfired Gaza rockets, which Islamic Jihad has denied.
Islamic Jihad spurns coexistence with Israel and preaches its destruction.
Top ministers of Israel's religious nationalist government rule out any state sought by Palestinians in territories captured by Israel in the 1967 Middle East war.
