Police were called to Telford Avenue, SW2, at 7.43pm on Tuesday, 25 February to reports of an assault.
It was reported an unknown substance was sprayed at a man. London ambulance service and the London Fire brigade also attended.
The substance was found to be unharmful.
A man was arrested on suspicion of GBH but was then dearrested.
Both parties agreed to sort out the matter as a civil dispute.