A list of names and addresses was posted on a website linked to the group alongside a call for them to be killed.
The group said it obtained the information by hacking servers and databases but US officials said most of the data was in the public domain.
A US security source told the BBC that those on the list were being contacted.
The group, which called itself the Islamic State Hacking Division, said the personnel named had participated in US missions against IS.
It urged its supporters in the US to "take the final step" and "deal with" those named.
A US defense official, speaking on condition of anonymity, told US media: "I can`t confirm the validity of the information, but we are looking into it."
A spokesman for the US Navy`s law enforcement agency told the BBC that the personnel would be advised to check their online footprint and adjust their privacy settings.
The US and its allies have been conducting air strikes against Islamic State militants in Syria and Iraq since last September.
IS has seized large swathes of territory in both countries. Its brutal tactics, including mass killings and abductions of members of religious and ethnic minorities, have sparked outrage across the world.
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