Cops released surveillance pics Saturday of a teenager they say tried to rape an 11 years old boy in a Bronx park after telling the victim he had a knife and trying to rob him. The victim said police the teen grabbed him from behind and demanded cash on Magenta St. near White Plains Road in Williamsbridge about 3:15 Pm Tuesday. The attacker claimed he had a knife and steered the boy three blocks west to Bronx Park. Surveillance pics released by cops Saturday show the attacker walking on Magenta St with his arm around the boy. Inside the park, the man forced the victim onto the ground, again demanded cash and pulled the boy’s pants down. The boy was able to fight off his attacker, who bolted from the park. The would be rapist punched the boy in the face during the struggle but his injuries were not serious. Cops are asking the public’s help identifying and locating the suspect. He is described as light skinned and between 17 and 19 years old with a thin build and braces on his teeth. He was wearing a blue hoodie, white and blue sneakers and blue jeans.