Suon Da, 25, was knifed twice in the abdominal area by Sa Rida, a 24-year-old sex worker, during the fight at a brothel in Battambang province Wednesday, said Koam Roeuy, a deputy police chief from the area.
Koam Roeuy said Suon Da had paid Sa Rida 5,000 riel (US$1.20; euro0.90) to have sex with her. But after Suon Da repeatedly refused to wear a condom, Sa Rida gave up and left the room.
Suon Da chased after her, demanding his money back and slapping the woman, Koam Roeuy said. Sa Rida responded by stabbing Suon Da in the stomach, he said.
"The woman was trying to prevent the transmission of diseases such as HIV," Koam Roeuy said. But now it will be up to the court to decide her fate after she inflicted injuries on another person."
Sa Rida remains in police custody pending possible charges against her. Suon Da is being treated at a hospital in Battambang province, about 250 kilometers (155 miles) northwest of the capital Phnom Penh.
Cambodia has an HIV infection rate of 1.9 percent for people aged 15-49, among the highest in Southeast Asia.
Comprehensive education campaigns, including widespread condom use in brothels, has helped reduce the infection rate from 3 percent in 1997, according to the Cambodian government.