A man used a hammer to hit two women - one aged in her 30s and one in her 20s - in the popular shopping district on Friday night.
The man then entered a pub in Glasshouse Street where he hit a man and a woman.
The victims were taken to hospital but their injuries are not thought to be life threatening.
Police were called to the scene at around 11pm.
A 38-year-old man was detained by security guards at the pub and arrested by officers on suspicion of GBH.
He has been taken into custody at a central London police station.