In the video, Schwarzenegger is seen busy taking a Snapchat video while a young athlete warms up.
A man is then seen attacking the former governor of California from the back with a flying kick.
The attacker hits the floor, as the 71-year-old Schwarzenegger stumbles momentarily after contact.
The former movie star's security then manages to apprehend the man. It is not clear why the man attacked Schwarzenegger.
Schwarzenegger then took to social media to reassure fans there was nothing to worry.
Organisers of the festival also confirmed that the former movie star was fine and would not lay charges against his attacker.
"He views this as an unfortunate incident by a mischievous fan," organisers said in a statement.
Meanwhile, reaction continued to the bizarre incident, with many Tweeps questioning the motive behind the attack and rallying behind the legendary star.
See some reactions here:
What happened to #ArnoldSchwarzenegger is utterly disrespectful, embarrassing on our half really but hats off to how the icon held himself and carried on 🙏🏼 Dignified and Tall✨— Nosipho Hani Khumalo🇿🇦✊🏼 (@HaniKhumalo) May 19, 2019