Israeli Prime Minister Benjamin Netanyahu said on Friday that Hamas did not agree to release further hostages, infringing on terms of a truce, and that Israel remained committed to achieving its objectives as fighting resumed in the Gaza Strip.
Hamas did not release all women hostages as agreed and also launched rockets at Israel, Netanyahu's office said.
"With the resumption of fighting we emphasize: The Israeli government is committed to achieving the goals of the war - to free our hostages, to eliminate Hamas, and to ensure that Gaza will never pose a threat to the residents of Israel," it said.
Heavy fighting was reported in Gaza on Friday as Israel's military resumed combat operations against Hamas.
The seven-day pause, which began on Nov. 24 and was extended twice, had allowed for the exchange of dozens of hostages held in Gaza for hundreds of Palestinian prisoners and facilitated the entry of humanitarian aid into the shattered coastal strip.
In the hour before the truce was set to end at 7 a.m. (0500 GMT), Israel said it intercepted a rocket fired from Gaza.
There was no immediate comment from Hamas or claim of responsibility for the launches.
Palestinian media reported Israeli air and artillery strikes across the enclave after the truce expired, including in Rafah, near the border with Egypt.