Police are continuing to search for a man who allegedly sexually and indecently assaulted two sisters, aged two and six, in the toilet block of a western Sydney park.

The man fled from the park in Guilford after abusing the girls who were there with family on Thursday afternoon.

Police attended the park and conducted a search of the area with the assistance of the dog unit and Polair but were unable to locate the man.

After failing to find the abuser, detectives from the child abuse squad formed Strike force Sandyman to further investigate.

A police spokeswoman told AAP on Friday morning she believed the search for the alleged attacker would continue today.

Police are looking for a man described as being of Middle Eastern or Mediterranean appearance, between 20 and 30, about 165cm tall with an average build and facial hair.

He was last seen wearing a black hooded jacket and blue shorts or pants.

Anyone with information should contact Crime Stoppers on 1800 333 000.