Israel has repeatedly accused Hamas of using schools, mosques, hospitals and the vast tunnel systems beneath them as military bases – allegations the group denies.
On Thursday, military spokesman Daniel Hagari said Israeli troops had killed more than 2,000 Palestinian militants since a week-long ceasefire ended on December 1.
He did not elaborate on the source of his data.
According to data on the Israeli military’s website, 139 soldiers have been killed since ground attacks in Gaza began on October 27.
Hamas’ health ministry said five people were killed in an attack on a house in Rafah on Friday.
The UN human rights office in Ramallah said it had received reports that Israeli troops “summarily killed” at least 11 unarmed Palestinian men in the Rimal neighborhood of Gaza City this week.
An Israeli official, speaking on condition of anonymity, dismissed the allegations as “yet another example of a biased and prejudicial approach against Israel” by the UN body.
Israel is under increasing pressure from allies, including the United States, which provides it with billions of dollars of military aid to protect civilians.
The UN rights office said the “details and circumstances” of the killings in Rimal were still being verified, but that it “raises concerns about the possible commission of war crimes”.