Airwars, an NGO which monitors civilian casualties from air strikes worldwide, estimates more than 7,900 civilians have been killed in coalition raids -- well in excess of the total acknowledged by the coalition.
The Syrian Observatory for Human Rights, a Britain-based monitor, says coalition strikes have taken the lives of 3,800 civilians in Syria alone.
IS jihadists seized large swathes of Iraq and Syria in 2014, declaring a "caliphate" in areas they controlled.
But several offensives with coalition backing chipped away at the "caliphate" until it was declared eliminated on March 23.
Ambushes and hit-and-run attacks have continued in both countries.
The coalition is continuing to work "to deny Daesh any physical space and influence in the region as well as deny Daesh the resources they need to resurge", it said, using an Arabic acronym for IS.
The US-led coalition said Friday it had unintentionally killed more than 1,300 civilians in air strikes during its fight against the Islamic State group in Iraq and Syria since 2014.