"We ask (Israel) to redouble their efforts moving forward to prevent civilian casualties, given the events of the last couple of days," State Department spokeswoman Jen Psaki told reporters.
"We believe that certainly there is more that can be done."
Psaki called images of the childrens deaths "horrifying" and said that Secretary of State John Kerry has raised concerns directly with Israel.
"The tragic event makes clear that Israel must take every possible step to meet its standards for protecting civilians from being killed," Psaki said.
Footage of Wednesdays killings of four Palestinian children on a beach in Gaza by an Israeli strike was broadcast around the world.
Officials said that four more children were killed on Thursday, including at least three from the same family between ages seven and 10 in a Gaza City house.
Psaki reiterated that the United States has "strong concern" about Hamas and urged the militant group to stop firing rockets into Israel, the trigger for the military action.(*)
Editor: Heru Purwanto
Copyright © ANTARA 2014
