Roscoe Holyoake, a 34-year-old from Perth known as DJ Roski, entered not guilty pleas to kidnapping and child endangerment charges on Thursday.

He remains in San Francisco County Jail after Superior Court Judge Vedica Puri sided with prosecutors and ruled to keep him in custody without bail.

Holyoake's lawyer, Stephen Olmo, told the Bay City News Service he had been in touch with Holyoake's family and friends in Australia who all said the allegations did not match his character.

"There was no evil intent," Olmo said.

The lawyer added Holyoake's alleged actions may have been the "result of having some kind of break ... a mental disengagement from reality".

Prosecutors allege the incident occurred last Friday when a mother was pushing a stroller on San Francisco's 17th Street and her young son was following closely behind her.

When the mother was putting her mobile phone in her pocket she allegedly saw Holyoake carrying her son with his arms wrapped around the child's buttocks.

A "tug-of-war over the child" allegedly then began between Holyoake and the mother who yelled: "What are you doing?"

Holyoake allegedly released the boy after the struggle, smiled and ran away but bystanders chased him and held him until police arrived.

The boy suffered redness on his arms.

Holyoake faces up to eight years in prison if convicted.

Australian Associated Press