A Broome man accused of cable tying three young Aboriginal children and leaving them in the heat after finding them swimming in a pool at a vacant property has pleaded not guilty to three counts of assault.

On Monday, Matej Radelic, 45, faced Broome Magistrates Court, where he was charged with three counts of common assault in circumstances of aggravation or racial aggravation.

Mr Radelic said he understood the charges, before pleading not guilty, the ABC reported.

The incident made national headlines after a video of two Aboriginal children appeared to show them being restrained at the wrists by black cable ties and sitting on the ground crying.

Temperatures on the day reached 33 degrees.

Police have previously said they were called to the home on Conkerberry Road about 2.15pm on March 5 in the Broome suburb of Cable Beach for a reported trespass incident.

Officers arrived a short time later and alleged they found two children - the six-year-old girl and seven-year-old boy - being physically restrained.

They later said a third child – aged eight - left the scene prior to police arrival.

Police alleged they received a call from Mr Radelic telling them he had "restrained" three children, allegedly for causing damage.

The video footage prompted concern for the children, with Noongar academic and human rights law expert Dr Hannah McGlade arguing the "shocking incident has shown the ugly face of racism in Western Australia".

Police publicly rejected claims made on social media that a video purporting to show damage to a Broome home was caused on the day the children were allegedly assaulted - which sparked a flurry of racist comments, because the footage was of an unrelated matter.

Roberta Cox, a relative of the children, previously told The West Australian the cable ties were so tight they broke the skin and drew blood.

More than $5000 was raised by a community fund to buy the children a new pool, and pool toys, after the incident came to light.

Mr Radelic's first hearing was due on March 25 but was adjourned for legal advice.

Magistrate Deen Potter granted Mr Radelic bail under the same terms as his first hearing, extended to the date of his trial.

He is due to reappear in court again on September 12.