Marc Garlasco, a senior military analyst with the group, said on Tuesday that the drone operators had fired at least six times before verifying their targets during the Gaza War and killed at least 29 civilians, among them 8 children.
In six cases documented in the report, three attacks hit children playing on rooftops in residential neighborhoods and three others hit an elementary school serving as a refugee center, a group of students at a bus stop, and a metal shop near a refugee camp.
The report says in each case, high-resolution video from the drones should have told operators there were no gunmen in the area.
Drones, operated by remote control by pilots watching their targets on a video monitor, are called "the most precise, the most distinguishing of all weapons that any military has in its arsenal".
"We were quite surprised during our mission in Gaza to actually find so many civilians killed by these weapons," Garlasco said.
While Palestinian witnesses and defense experts have reported seeing Israeli drones attacking targets on the ground, Israeli military has denied the report saying it appeared to be based on "unnamed and unreliable Palestinian sources" whose military expertise were "unproven," said a military spokesman on Tuesday.
The group however said it found a particular type of shrapnel and a neat dispersion of the missile parts consistent with a drone-fired Israeli Spike missile.
Israel launched its three-week war against Gaza in late December. Some 1,400 Palestinians, including more than 900 civilians, were killed, according to Gaza health officials and human rights groups.