The judge said she was satisfied the boxer was defending himself during the incident.
A judge determined that Joe Cordina's response was warranted
Former boxing world champion Joe Cordina has been cleared of assaulting a man he punched outside a petrol station.
The incident outside a garage in Pentwyn, Cardiff, in February led to the 34-year-old being denied entry to the US for a WBO lightweight title clash.
District Judge Charlotte Murphy found Cordina not guilty of assault by beating against Jamie O'Brien, 33, following a trial at Cardiff Magistrates' Court.
She said she was "satisfied" Cordina believed it was necessary to use force to defend himself.
"I am further satisfied that a single, measured, controlled punch was proportionate in the circumstances," she said.
"It is very easy to consider the defendant's response by considering the CCTV in slow motion, however the defendant had a split second to consider his response to the shoulder barge."
Source: BBC Sport