Investigators with the Special Victims Unit said the suspect broke into the home shortly after 7 a.m. ET.
Police said the girl was not injured in this incident and the suspect fled on foot after the assault.
It's not clear how the suspect entered the home.
Police describe the suspect as a 5'10" brown male, who is approximately 15 years old. He was last seen wearing a red T-shirt, black shorts and flip flop sandals.
Police are reminding the public to secure all doors and windows before leaving their residence, or going to bed at night.
Anyone with information about the incident is asked to contact the Special Victims Unit at 905-453-2121, ext. 3460, or Peel Crime Stoppers at 1-800-222-8477.