"We're disappointed with the verdict, but we respect the process. It was a close case," Dan LaBelle said.
An American-born convert to Islam, Abu-Jihaad was said to have passed on details that included the make-up of his navy battle group of ships and its planned movements.
He was also said to have passed on a drawing of the group's formation when it was to pass through the dangerous Strait of Hormuz in the Gulf on April 29, 2001.
UK case link
He was charged in the same case that led to the 2004 arrest of Babar Ahmad, a British computer specialist accused of running websites to raise money for alleged terrorists.
Ahmad is currently fighting extradition to the US.
Prosecutors said that investigators had uncovered files on a computer disk recovered from Ahmad's house that contained the ship movements, as well as the number and type of personnel on each ship and the ships' capabilities.
Prosecutors also said Abu-Jihaad exchanged emails with Ahmad in 2000 and 2001 while on active duty on the USS Benfold in which he discussed naval meetings and praised Osama bin Laden.
"This verdict demonstrates loudly and clearly that we will seek to hold accountable anyone responsible for providing classified information to those who intend to use it in a manner against our national interests," Kevin O'Connor, the Connecticut US attorney, told AFP.
However, Abu-Jihaad's lawyer said that much of the material was already widely available through news reports, press releases and websites.
He also said that navy officials had testified during proceedings that the information was full of errors.