Residents in the village of al-Lihaib near the town of Garma, said 24 people had been killed and some buildings levelled in the assault.
The attack is the latest of several recent raids during which women or children have been killed or wounded by US forces in residential areas.
US-led forces said they found weapons along with the bodies of the women and child after searching through one of the buildings that was destroyed.
The military did not provide the age of the women or the age and sex of the child. Three suspected men also were detained.
Güncelleme Tarihi: 20 Eylül 2018, 18:16
Baby and teenagers killed
Garmah, 80km west of Baghdad, is in Anbar province, a large area of western Iraq where many of the country's Sunni Arab armed groups operate.
The US military said in a statement: "After the air strike destroyed the building, coalition forces were able to determine that five terrorists, along with two women and one child, were killed."
In another US air raid on Friday near Taji, just north of Baghdad, one man was killed and a woman in her 50s wounded. US military officials said she "... was being used as human shield by the terrorist".
"Terrorists continue to deliberately place innocent Iraqi women and children in danger by their actions and presence," the statement said.
On Wednesday, two Iraqi women died when US forces backed by aircraft killed eight al-Qaeda-in-Iraq insurgents during a raid near Baqouba, 60km northeast of Baghdad, the military said.
A day before, American soldiers killed a seven-month-old-baby and four girls aged between 12 and 17 after fighting with suspected armed groups in Ramadi, the capital of Anbar province. One man was also killed, the US command said.
Another Iraqi woman was wounded. The military quoted residents as saying the building attacked "was a known anti-Iraqi force safe house".