"Please Lord Buddha help make our leaders listen when we say that the new law does not protect us," said Su Sotheavy, 68. "Our families depend on our profession."
Police began rounding up male and female sex workers from brothels, bars and parks in March. The law does not specifically target sex workers but activists say it prompted authorities to take a tougher stand against prostitution.
Earlier this month, some 200 Cambodian sex workers protested against the crackdown and alleged that some of them had been physically and sexually abused in custody.
Cambodian law does not explicitly define prostitution as illegal, but commercial sex is frowned upon by authorities who routinely launch sweeps to clean up the streets.
Some sex workers at the protest said they were married with children and their families relied on their job.