The free Samhuinn show, held every Halloween on the Royal Mile, is thought to be at risk from city council plans outlining no music after 6pm and guidance on processions.
Yet the council have assured the consultation they launched is to clarify existing rules rather than any new crackdown.
Samhuinn organisers The Beltane Fire Society are now urging people to back their event in feedback to the council before the end of the month.
“We fully understand the council needs to do everything it can to make sure local residents and businesses aren’t unduly inconvenienced by activity in the city centre,” said Beltane Fire Society chair Erin MacDonald.
“We support that and have a positive relationship with the council but it’s about striking a balance with maintaining our cultural heritage.”
Ms Macdonald said a ban on music after 6pm posed particular problems for fire festivals.
“We’re used to adhering to strict regulations,” she said. “But the thing about fire festivals is they have to have drums and have to be at night.”
The council plans also include recommendations that procession participants walk in rows of no more than four side-by-side.
“We fundamentally believe the proposals in their current form are inconsistent with freedom to assemble in Edinburgh,” said Ms Macdonald.
“Community events need to be protected and maintained on the Royal Mile because otherwise you’re saying it’s only for corporate or military events.
“That it’s only for tourists and for people with money - and that would be a huge shame.”
Ms MacDonald said it would be “insufficient” for the council to provide Samhuinn special dispensation as a long-standing event, while other community events are affected.
She said the Help Save Samhuinn campaign has already attracted support on social media in the first 24 hours since launch.
“We want to translate that into the people of Edinburgh stepping up to protect our cultural heritage. We want to keep Edinburgh for the people of Edinburgh,” added Ms MacDonald.
A Council spokesperson said: “We are currently consulting the public on proposed guidance for holding marches and parades in Edinburgh. However, there are no plans to increase restrictions on such events.
“By developing a detailed policy and code of conduct we aim to provide a greater understanding of its expectations to organisers, as well as a consistent approach for event planning, rather than introducing new controls.”