A jury in North Dakota convicted Cruz of terrorizing his then-girlfriend's 13-year-old son in 2007 by holding a knife to his throat.
Court documents also show Cruz was found not guilty of a misdemeanor charge for domestic violence filed in the same case.
Cruz's failure to report his conviction did not automatically result in removal of his license. California was notified by the Burleigh County clerk's office in North Dakota.
"The board looks at the facts of each individual case before making a decision," said California Medical Board spokeswoman Jennifer Simoes. "For this particular case, it found Cruz's actions were substantially related to his duties as a physician."
Cruz did not hire an attorney to defend the charges, Simoes said.
A phone number listed for Cruz's office was not accepting calls.
It was not the first time Cruz caught the notice of the state medical board. In 2003, he received a public reprimand after falsely reporting a patient's condition.
Cruz admitted to the medical board that he failed "to accurately and truthfully fill-out the doctor's certificate section" of his patient's disability benefits form.
The patient was admitted to the hospital with complaints of numbness in her left hand and face, as well as dizziness and nausea.
Cruz falsely stated the patient was a possible drug abuser in an alcoholic recovery or drug-free facility and that she was "capable of performing her regular work at all times even though she was hospitalized for five days."
Over the past 10 years, Cruz has worked at offices at 2601 W. Alameda Ave., 4318 W. Victory Blvd. and 150 S. Glenoaks Blvd.