According to the Telegraph, Annaliese Burgess said: "(Oscar Pistorius and his cousin) sat in a quiet area of the private VIP section when they were approached by the individual," she said.
"The individual in question, according to our client, started to aggressively engage him on matters relating to the trial.
"An argument ensued during which our client asked to be left alone. Oscar left soon thereafter with his cousin.
"Our client regrets the decision to go into a public place and thereby inviting unwelcome attention."
However, the man named by local media as Jared Mortimer claimed that the Paralympian was "drunk and very aggressive".
Oscar has rarely been seen in public since the night he shot his girlfriend. He says he mistook her for an intruder in the early hours of the morning, while the prosecution claims that he killed her in anger after a fight.
Following the incident at the weekend the 27-year-old has been tweeting inspirational images – his first appearance on social media since he posted a message on the anniversary of Reeva's death on February 14.
One was a collage of pictures of him posing with amputee children with the caption: "You have the ability to make a difference in someone's life."
Another asked God to "bathe those who live in pain in the river of your healing". He also quoted a passage from The Bible that read in capitals "THE LORD IS CLOSE TO THE BROKENHEARTED" but this was later removed.
Oscar also posted a section from the best-selling book by Austrian psychiatrist Victor Frankl, who was an Auschwitz survivor and talks about finding solace in his "utter desolation" by contemplating a picture of his "beloved".
The nightclub incident came as the athlete waits for closing arguments in his trial. These are due to take place on August 8 and 9.
Under the South African justic system presiding, which does not use jurors, Judge Thokozile Masipa will then consider her verdict, which could take a month.