O'Neal was arrested along with his son, Redmond, after authorities searched their home early Wednesday. The search was part of a routine sweep by deputies checking on Redmond O'Neal, who remains on probation after pleading guilty earlier this year to a pair of drug possession felonies.
The pair were released after posting $10,000 bail. Los Angeles County prosecutors will evaluate whether to press charges against the men.
Werksman said the elder O'Neal was "shaken up" by the arrests. "We know that when all the facts come out, he should not be charged with any crime here."
The lawyer did not address any role O'Neal's son may have played, and said he did not know who was representing Redmond O'Neal.
A sheriff's spokesman said Wednesday that Ryan O'Neal was arrested after drugs were found in his living area. The drugs were suspected to be methamphetamine.
"He's tried to lead a peaceful life," Werksman said of Ryan O'Neal. "He's acting and he's caring for his family and this is the last thing he ever wanted or expected."
O'Neal, 67, was nominated for a best actor Academy Award for 1970's "Love Story." Redmond, 23, is his son from a relationship with Farrah Fawcett.
O'Neal had two children with his first wife, Joanna Moore: actor Griffin O'Neal and actress Tatum O'Neal, his co-star in the 1973 movie "Paper Moon," for which she won an Oscar for best supporting actress.
In July, Tatum O'Neal pleaded guilty to disorderly conduct in connection with an arrest on suspicion of cocaine possession in New York.
On Thursday, she issued a statement of support for her father and half brother.
"Addiction, if untreated, can lead to jail, institutions and death. I love them both and I am sorry to hear about this," she said.