Rare Steakhouse venue manager Arryanne McIntosh said the group had loudspeakers and "were repeating propaganda and stuff relating to consumption of meat".
"It was hard to communicate with them," she said. "I asked who was in charge and one lady said 'we all are'. We were trying to talk to them but they were quite in-your-face with talking and speaking over the top of you — they were very loud, yelling."
McIntosh said staff called the police, who took about 15 minutes to arrive. She described it as "very upsetting" for customers and staff. "You're coming in for dinner and spending X amount of money — you don't want people yelling in your face," she said.
"A couple of tables were very upset, to be honest, one table in particular was very emotional. We just did the best we could to calm the people, give them comfort that the police were coming."
She said her staff handled the situation well, but "a couple of them were upset" that the protesters were pushing video cameras in their faces even though they asked not to be filmed.
"I don't know if they targeted us for a specific reason. The police said it might happen again, but the best thing to do is just call them," she said.
A Victoria Police spokesperson said theprotesters left peacefully when asked to do. "There were no arrests and no injuries."
The restaurant's website says it chooses meat based on its impact on the environment and use of sustainable farming practices.
Commenters on Facebook had mixed reactions to the stunt. "Great work! If people want to eat the corpses and secretions of animals then they can face the hard truth of how it ended up on their plates," Katrina Larsen wrote.
But Amber Marie said she was vegan and "this is not cool".
"Best way for non-vegans to think ill of vegans," she wrote. "People are spending money, buying a meal, uniting with family, celebrating their life's joys, on dates. You have successfully ruined these moments for them, they will never want to hear from a vegan again."