Smith's attorney entered the plea on her behalf Monday without her appearing, said Orange County district attorney's spokeswoman Susan Schroeder.
She was also ordered to perform 80 hours of community service and pay $1,300 (EUR953) in fines and penalties.
Smith, 19, was arrested in March for investigation of felony driving under the influence of alcohol after crashing a Volkswagen Beetle into another car on the San Diego Freeway, according to a California Highway Patrol report.
The driver of the other car suffered minor injuries as did a passenger in the car driven by Smith, the report said.
Although Smith was arrested for investigation of felony DUI, the charge was lessened to a misdemeanor because the injuries were not serious, officials said.
Experts believe that the rate of the Russian ruble may collapse again just like it happened during the crisis in 2014. In turn, Russian companies may deal with the shortage of currency to pay their debts
Austria does not intend to expel Russian diplomats because of the spy scandal