The Israeli military said it was responding to a breach of the ceasefire the previous day, in which its troops had identified eight gunmen emerging from a tunnel in Rafah, an area in the south of the enclave controlled by Israeli forces under the truce.
It had targeted commanders, weapons caches and manufacturing sites belonging to Palestinian militant group Hamas and its ally Islamic Jihad, the military said.
Hamas, which retains control of just under half of the Gaza Strip where nearly all its more than two million residents live mainly in makeshift tents and damaged buildings, said Israel had violated the truce.
It did not say whether any of its members or sites were struck in Saturday's attacks.
On Sunday, Israel is due to reopen the Rafah border crossing between the Gaza Strip and Egypt under US President Donald Trump's plan to end the war.
The war began after Hamas-led gunmen attacked southern Israel on October 7, 2023.
Israeli officials have said the war could resume if Hamas does not lay down its weapons.
Israeli warplanes bombed the Sheikh Radwan police station west of Gaza City, killing 13 people, including five officers, police in Gaza said.
Rescue teams were searching for more casualties at the site, the Hamas-run police said.
Other air strikes hit at least two houses in Gaza City, in northern-central Gaza, and a tent encampment sheltering displaced Palestinians in Khan Younis further south, local officials said.
Video footage from Gaza City showed charred, blackened and destroyed walls at an apartment in a multi-storey building, and debris scattered inside it and outside on the street.
Samer al-Atbash said the bodies of his three small nieces had been found in the street.
"They say 'ceasefire' and all. What did those children do? What did we do?" he said.
The Gaza civil defence rescue service put Saturday's death toll at 32.
Israel said that in Friday's encounter with fighters in Rafah its soldiers killed three and arrested a fourth, described as a Hamas commander.
Hamas did not comment on the incident.
Dozens of its fighters have been trapped in tunnels under Rafah since the ceasefire although some have since been killed in clashes with Israeli forces.
Violence has repeatedly shaken the ceasefire.
Israeli fire has killed more than 500 people, most of them civilians according to Gazan health officials, and Palestinian militants have killed four Israeli soldiers, according to Israeli authorities.
The two sides have traded blame over truce violations, even as US officials press them to proceed to the next phases of the ceasefire deal, which is meant to end the conflict for good.
The next phase of Trump's Gaza Strip peace plan includes complex issues such as Hamas disarmament, which the group has long rejected, further Israeli withdrawal from the strip and the deployment of an international peacekeeping force.
Reuters reported on Monday that Hamas is seeking to incorporate its 10,000 police officers into the new US-backed Palestinian administration, a demand likely to be opposed by Israel.
