The incident happened at Hawthorn Street in the Clonard district this afternoon, Thursday, October 29.
The victim has been taken to the Royal Victoria Hospital for treatment.
Police said the man’s condition is not known at this stage.
Part of Hawthorn Street has been closed while the crime scene investigators carry out a fingertip examination.
Police are appealing to anyone who was in the Hawthorn Street area this afternoon and who witnessed an altercation to contact officers at Woodbourne Police Station on the non-emergency number 101.
Information can also be passed anonymously through Crimestoppers on 0800 555 111.