Avon and Somerset Police issued the image on Monday after a man was stabbed in Shirehampton, Bristol.
The similarity was pointed out on social media and reported by the Bristol Post.
The police have since issued an altered picture and said "whatever the map may have resembled should not distract from the severity of the crime".
A police spokesman said: "This is a serious appeal for information after a man was left in need of hospital treatment following a violent assault.
"Whatever the map may have resembled should not distract from the severity of the crime and our request for help from the public."
The 26-year-old victim remains in a critical but stable condition in hospital, after the incident last Friday, the police said.
A 27-year-old woman and a 30-year-old man have been arrested and have been released on bail pending further inquiries.
A map issued by police trying to find witnesses to an assault looked like a "giant penis", it was claimed.