Authorities met the vehicles in the parking lot, where they witnessed Lohan and the woman in "heated debate," Padilla said. Lohan and the woman each had two passengers in their respective vehicles.
The actress recently completed a 45-day program at the Promises facility, where she checked in after crashing her Mercedes in May.
Late last Thursday, Lohan went to the Beverly Hills Police Department to be fingerprinted, photographed and booked on a suspicion of driving under the influence tied to that accident. She had an Aug. 24 court appearance in connection with that case, for which she also faces a misdemeanor hit-and-run charge.
Lohan's blood-alcohol level during the May crash was above the legal limit, according to police. Lohan and two other adults were in her car when she lost control and crashed into a curb on Sunset Boulevard, police said. The actress left the scene of the crash in another car to treat minor injuries at the hospital.
Leslie Sloan Zelnik, Lohan's publicist, said the actress would voluntarily wear the alcohol monitoring bracelet after she left rehab.
"In part she is wearing the bracelet, so there are no questions about her sobriety if she chooses to go dancing or dining in a place where alcohol is served," Zelnik said in a statement at the time.
An assistant to Zelnick told ABC News that the publicist was serving jury duty and was not available for comment.
Padilla said he wasn't sure if Lohan was wearing the device when she was stopped Tuesday morning.
Lohan had been expected at a taping of "The Tonight Show with Jay Leno" to promote her film "I Know Who Killed Me," which opens Friday.
It's unclear exactly how this latest episode may affect Lohan's acting career, but it's unlikely to help. Already, her unpredictable behavior has caused on-set problems.
A year ago, James G. Robinson, CEO of Morgan Creek Productions, wrote Lohan a letter threatening legal action against her for acting like a "spoiled child" and her "irresponsible and unprofessional" behavior.
In it, Robinson writes that despite Lohan's repeated claims of illness for missing work, the production company knew about her continual partying. "We are well aware that your ongoing all night heavy partying is the real reason for you so called 'exhaustion,'" Robinson wrote. "We refuse to accept bogus excuses for your behavior."
Michael Lohan, the actress's estranged father who recently completed a two-year DUI prison sentence, told TMZ.com that he took some blame for his daughter's string of police run-ins involving cars, alcohol and drugs. He also said he wanted to put a stop to his bitter custody battle with Dina Lohan involving the couple's two younger children so the family can rally behind the struggling star.
"I want to withdraw everything -- courtwise -- sit down with Dina as Lindsay's parents and figure out how to help her," Michael Lohan told TMZ.com. "Lindsay can't do this on her own. … When we were together, none of this was happening."
Lohan's father also said shortly after his daughter's May incident that she suffers from various addictions, including alcohol and the painkiller OxyContin.
Information from The Associated Press was used in this report.