Shahid Khan, 30, who lives in Glasgow's West End, was head butted, slapped and racially abused as he walked with his sister near Anniesland Cross.
Police are hunting for the thug who assaulted Mr Khan shortly before 4pm on Tuesday.
Mr Khan said: "I was walking from Anniesland Retail Park with my sister and this man started shouting at me.
"He said to me: 'Are you responsible for trafficking women in this area?'
"I found this offensive but my sister told me not to get involved or make eye contact."
Mr Khan, a writer who fled to Glasgow almost two years ago after being persecuted in his home country of Pakistan, continued to try to ignore the man.
Mr Khan said: "The next thing I knew he headbutted me in the back of my head then headbutted me in the forehead.
"He then started to shout things like: 'Go back to your own country.'"
Mr Khan, whose nose was bleeding at the time, then began to try to fight back in self defence.
Customers at BJ's Bar and Diner in Crow Road rushed out to try to stop the brawl.
Mr Khan said: "Three or four men from the bar came to try and help me but the man ended up trying to fight them."
The man, who is thought to be aged between 20 and 26, fled the scene before police arrived.
Mr Khan said: "This was a horrendous and hideous act and I'm now paranoid about leaving my home."
Officers are gathering CCTV images and continuing inquiries.
They are appealing for witnesses to what they described as "a racial incident".
The suspect is described as having short brown hair, being clean shaven and wearing a dark coloured jacket and cap and blue jeans.
Chief Inspector Fraser Lamb, who is investigating the incident, said: "This was a totally random attack.
"It is not acceptable for people to think they can go around physically abusing people.
"I would urge anyone who was in the area at the time to please get in touch with us."
Anyone with information can call Drumchapel Police on 0141 532 3600 or Crimestoppers on 0800 555 111.