An Indonesian masseur has been charged with inappropriately touching a 12-year-old Perth boy during a massage in Bali's Kuta tourist district.

Police said the boy went to the Damen Massage business with his mother and grandmother on Saturday and was taken to a separate treatment room to his relatives.

Kuta Police Chief I Wayan Sumara said the masseur, 47-year-old Abdurahman, asked the boy to take off his clothes and change position.

Police allege Abdurahman then touched the boy's genitals and pulled down his own pants.

"Then the victim got up and hurried out, and called his mother and his grandma," I Wayan Sumara said.

During interrogation Abdurahman allegedly told police that he intended to rape the boy, and said that he had committed similar offences on 15 other occasions, including when he had worked at another spa.

Police have charged Abdurahman with sexual harassment, which carries a penalty of between five and 15 years in jail.

A Department of Foreign Affairs and Trade spokesperson said the boy and his family were receiving consular assistance, but no further information would be released for privacy reasons.