HAVANA (AP) — Raul Castro seemed rattled.

The Cuban president sent for the top American envoy in the country to address grave concerns about a spate of U.S. diplomats harmed in Havana. There was talk of futuristic "sonic attacks" and the subtle threat of repercussions by the United States, until recently Cuba's sworn enemy.

The way Castro responded surprised Washington, several U.S. officials familiar with the exchange told The Associated Press.

In a rare face-to-face conversation, Castro told U.S. diplomat Jeffrey DeLaurentis that he was equally baffled, and concerned. Predictably, Castro den...