Mohammed al-Jishy told AFP the verdict was announced in the absence of Khawaja, who said on Sunday she would not attend the hearing because it was "impossible to have a fair and independent trial" in the Persian Gulf kingdom.
Khawaja, a director of the Beirut-based Gulf Centre for Human Rights, also holds Danish nationality and is a daughter of jailed top opposition figure Abdulhadi al-Khawaja.
She has been in London since a travel ban was lifted on October 1, Jishy said.
Khawaja was arrested after upon at Manama airport on August 30 on alleged charges of hitting two policewomen. She insists it was police who attacked her.
She was granted bail on September 18 pending trial.