One Palestinian has been killed and five others injured in an Israeli air strike in the northern Gaza Strip, Palestinian security officials said.
The Israeli army said the raid had targeted "three members of a Qassam rocket-launching cell that had just fired a rocket towards Israel".
Earlier, one person in the Israeli border town of Sderot was hurt in a rocket attack, Israeli medics said.
Israel resumed air strikes on Gaza on Tuesday after a six-month lull.
It followed several rocket attacks on Israel.
The attacks come amid a week of fighting between Hamas and rival Palestinian faction Fatah, which has left at least 40 people dead in Gaza.
Correspondents say the rocket attacks on Israel appear to be an attempt to draw it into an internal Palestinian conflict, although the Israeli defence ministry has denied its attacks are linked to factional fighting.
On Saturday, Hamas and Fatah announced that they had reached a new ceasefire deal which would come into effect at 1500 (1300BST).
Under the agreement, "armed men will leave their positions in buildings and streets, will remove road blocks and release hostages on both sides".
It is the fifth ceasefire the rival factions have signed since fighting began last Sunday.
Shortly before the Israeli air strike close to Beit Hanoun, Israel's Defence Minister Amir Peretz warned that there would be no let up in Israel's attacks on Hamas and that militants firing rockets onto Israeli soil should be "very afraid".
"We are mainly focusing on sensitive locations tied to Hamas," Mr Peretz told Israel Radio, saying that this included places where rockets are manufactured.
There have been numerous failed ceasefires in recent days
"The Palestinians need to understand that Hamas is leading them into disaster, a real disaster," Mr Peretz said. "It is our intention to act against Hamas."
Five people - four of them fighters loyal to Hamas - were killed in Israeli air strikes on Friday. The day before, six Palestinians died.
On Sunday, the Israeli cabinet is to consider whether to escalate its response.
"In the next few days, Israel is going to make some decisions," Reuters news agency quoted Foreign Minister Tzipi Livni as saying.