The 2009 photo, which showed the singer’s bruised face, was published on US gossip site TMZ.
However, prosecutors said they did not have enough evidence to show TMZ paid the accused officers for the image.
Rihanna’s lawyer said he did not know whether the singer intended to pursue any further legal action.
Officers Blanca Lopez and Rebecca Reyes are due to appear before disciplinary panels in August and may lose their jobs.
Brown, who was Rihanna’s boyfriend at the time, was sentenced to 180 hours community service and five years probation after admitting the attack in February 2009.