"Your question suggests that we made some kind of determination that the law was violated in the armed conflict, but we did not," RIA Novosti quoted him as saying.
Kirby stressed that Washington will not give its assessment of each new case of civilian casualties in strikes on the Gaza Strip.
He added that Israel has the right to defend itself.
Earlier, the deputy head of the press service of the US State Department, Vedant Patel, said that the United States does not support the forced resettlement of Palestinians outside the Gaza Strip.