At least eight Palestinians, most of them children, were killed and more than a dozen were wounded in central Gaza when they went to collect water on Sunday, local officials said.
The Israeli military said the missile had intended to hit an Islamic Jihad militant in the area but that a malfunction had caused it to fall "dozens of meters from the target".
"The IDF regrets any harm to uninvolved civilians," it said in a statement, adding that the incident was under review.
The strike hit a water distribution point in Nuseirat refugee camp, killing six children and injuring 17 others, said Ahmed Abu Saifan, an emergency physician at Al-Awda Hospital.
Water shortages in Gaza have worsened sharply in recent weeks, with fuel shortages causing desalination and sanitation facilities to close, making people dependent on collection centers where they can fill up their plastic containers.
Hours later, 12 people were killed by an Israeli strike on a market in Gaza City, including a prominent hospital consultant, Ahmad Qandil, Palestinian media reported. The Israeli military did not immediately comment on the attack.
Gaza's health ministry said on Sunday that more than 58,000 people had been killed since the start of the war between Israel and Hamas in October 2023, with 139 people added to the death toll over the past 24 hours.
Negotiations aimed at securing a ceasefire appeared to be deadlocked, with the two sides divided over the extent of an eventual Israeli withdrawal from the Palestinian enclave, Palestinian and Israeli sources said at the weekend.
Israeli Prime Minister Benjamin Netanyahu was set to convene ministers late on Sunday to discuss the latest developments in the talks, an Israeli official said.
The indirect talks over a US proposal for a 60-day ceasefire are being held in Doha, but optimism that surfaced last week of a looming deal has largely faded, with both sides accusing each other of intransigence.
Netanyahu in a video he posted on Telegram on Sunday said Israel would not back down from its core demands - releasing all the hostages still in Gaza, destroying Hamas and ensuring Gaza will never again be a threat to Israel.