The 44-year-old actor claimed to have been robbed of his cell phone in Geraldine Mary Harmsworth Park in Lambeth, London, mentions People magazine.
Scotland Yard confirmed that a man was treated for a head injury at St Thomas's Hospital, adding that he reported a robbery only to withdraw his complaint.
In an interview to BBC Radio Spacey told it like it is, "What actually happened is, I fell for a con. I was incredibly embarrassed by it. Some sob story about somebody needing to call their (sic) mother and could they use my phone."
So convincing was the stranger that the Oscar winner, who was strolling in the park because his 'doggy had to go' actually dialled the number for him. "This kid took off and I was so upset I ran after him," he told BBC Radio.
In doing so, he tripped over his dog, fell on the street and injured his head. "I feel like the biggest fool that has ever lived," says the actor.
Spacey lodged a complaint at the police station. But the next day, he changed his mind because he thought there was a 'difference between assault and theft'.
The star of The Usual Suspects, American Beauty and Seven apologised to the police, readers and anyone who picks up this story thinking it is true.
"I am fine. It is probably good that I got bumped on the head because obviously I wasn't thinking."