The UN has said that US-led coalition and Iraqi forces have a "collective responsibility" to protect civilians in the battle for Mosul.
The body said it was "deeply concerned" after civilians were killed in a coalition airstrike meant to target a van carrying Islamic State group fighters on Thursday.
The attack took place "in what was later determined to be a hospital compound parking lot resulting in possible civilian casualties", a statement from CENTCOM, the US military command in the Middle East, said.
"Families trapped inside Mosul are already extremely vulnerable and in need of protection," said Lise Grande, the United Nations Humanitarian Coordinator for Iraq.
"It is crucially important that all parties do everything possible to protect civilians in accordance with international humanitarian law, both during and after the conduct of hostilities. This is a collective responsibility."
The UN statement on Friday added it was particularly concerned by a "significant increase" in trauma injuries over the last month, with almost 1,000 people referred from Mosul to hospitals in Erbil since 19 December.
"Nothing is more important than the sanctity of life," Grande said.
"Protecting civilian infrastructure is also crucial. As military operations push deeper into the inner urban districts of Mosul, the utmost care must be taken to avoid damaging hospitals, schools, water stations and other infrastructure that sustains civilians."
The coalition has previously insisted it is taking extensive precautions to avoid killing civilians during its bombing of IS group targets, claiming it routinely uses precision-guided bombs or missiles to hit targets that are often observed by drones for hours before being hit.
"We appreciate the efforts being made by the Combined Joint Task Force and Iraqi Security Forces to limit destruction - and call upon all parties to conduct hostilities in ways which are consistent with international standards and humanitarian law," Grande added.
Since launching the second phase of the assault on 29 December, a further 2,000 people have fled the city, bringing the total displaced by the two-month long campaign to 118,000.