Police are searching for the Good Samaritan after he intervened to try to stop the alleged attack on the woman at the Tam O' Shanter bar on Great Junction Street.
Officers are hoping the man may be able to help with their inquiries into the incident, which took place at around 7pm on Sunday, November 14.
An argument broke out between the woman and her alleged assailant, ending with the woman being pushed to the ground.
The elderly man, believed to be in his 60s and walking with a cane, stepped in to help, but was himself assaulted, suffering a facial injury.
A 36-year-old man has been arrested and charged in connection with both assaults, and appeared at Edinburgh Sheriff Court on Monday.
A police spokesman said: "The man showed real bravery to intervene in the assault, and we need to trace him in order that he can assist us with our inquiries."