Press Secretary Josh Earnest Friday said the US extended "profound condolences" to the family and extended prayers for those injured in the attack to make a full recovery.
Witnesses and the Israeli military said that under cover of darkness, the attackers broke the windows of the family's home in Duma, a small village near the West Bank city of Nablus.
They lobbed a fire bomb into the sleeping family's bedroom which exploded into a fireball that quickly consumed the home.
The Israeli military said they were searching for the assailants.