The Israeli military did not immediately respond to a request for comment.
The American-born youth was 17 years old, the boy's uncle told Reuters, adding that the incident occurred during clashes with the Israeli military that included stone-throwing by Palestinians.
The Palestinian official news agency WAFA said the youth had been killed by Israeli gunfire.
Asked at a White House briefing on Friday, National Security spokesman John Kirby said: "We don't have perfect context about exactly what happened, but we're seriously concerned about it."
He added that the White House would be in "constant touch" with counterparts in the region to get more information.
(Reporting by Ali Sawafta and Nidal al-Mughrabi; additional reporting by Andrea Shalal in Washington; Editing by Sandra Maler)
