The Royal Mail worker was trying to deliver a parcel on Robert Street in Radcliffe at 12.45pm yesterday, Tuesday.
But he was approached by a man who “forcibly” took the parcel from him, causing him to be injured.
Police have now released two CCTV pictures of a man who may have information about the incident.
A spokesperson for Greater Manchester Police said: “On Tuesday, September 3, at 12.45pm, we were called to reports of a robbery of a Royal Mail operative who was trying to deliver a parcel to an address on Robert Street in Radcliffe.
“He was approached by a man who forcibly took the package, injuring the victim.
“We would like to speak to the man pictured as we believe he may be able to assist our investigation.
“If you have any information, or recognise the man in the pictures, please call police on 101 quoting log 1536 of 3/9/24 or Crimestoppers (anonymously) on 0800 555 111.”