A young chef who was stabbed while trying to prevent a woman from being strangled says he'd do it all over again because it's "insane" to see violence against women.

Luigi Spina, 24, paid a high price for stopping a vicious assault outside Melbourne's Crown Casino on Friday night.

The chef and avid kick-boxer had just knocked off work at a nearby eatery in Southbank when he saw the woman being attacked by a man just before midnight.

"He punch her in the face and then he put his arm on the neck like she couldn't breathe," he later told reporters.