At 10.20pm last night the occupant of a home on Beverley Road, Heaton answered his door to a man.
The man tried to force his way into the property while claiming he was a police officer.
The occupant – who is in his 60s –managed to close the door, preventing the man entering the property.
Police believe it was an isolated incident but are urging residents to be vigilant.
Detective Sergeant Robert Parker of GMP’s Bolton District said: “This was an unusual incident that has targeted a vulnerable member of the community.
“We are following various lines of enquiry and – while we believe this was an isolated occurrence – we would urge others to be mindful.
“We’re also appealing to anyone with information to contact police.”
Information can be left with police on 0161 856 5757 quoting incident 2454 of 27/02/19 or by contacting the independent charity, Crimestoppers, anonymously, on 0800 555 111.