The government has accused the Fire Brigades' Union (FBU) of putting lives at risk by calling a strike in London on Bonfire Night.
The 47-hour action, starting on 5 November, will be the third strike date since the FBU announced industrial action over new contracts.
It said the dispute centred on plans to scrap current rotas and force staff to sign new contracts or face the sack.
But Fire Minister Bob Neill called the latest planned strike "reckless".
FBU general secretary Matt Wrack said the proposed date of the industrial action was "obviously very serious".
He added: "Clearly if we get to that stage, and we still hope we can avoid getting to that stage, I think authorities who are for example arranging public displays will have to consider whether they all should go ahead."
Mr Neil said: "It's profoundly wrong and inappropriate to choose that particular time for the strike.
"The government's stayed out of the details of the dispute which is between the Fire Brigades' Union and their employers.
"But the timing of this particular strike I think is provocative. It's reckless. It actually puts Londoners' lives at risk in a needless way," the Conservative MP said.
The FBU said thousands of its members would walk out from 1000 GMT on 5 November until 0900 GMT on 7 November.
Last week, the FBU revealed that 79% of its members who had voted supported strike action.
Crews staged an eight-hour strike on Saturday and another is planned for Monday 1 November.
Mr Wrack said: "The date obviously is very serious, but any strike in the fire service is an extremely serious step for us to take and we don't want to be taking it.
"This can be resolved very quickly. Our members in London are facing mass dismissals, five-and-a-half-thousand of them are facing being dismissed.
"And if the sackings are lifted, there won't be any strike, either the one next week or the one on the weekend of the fifth."
Ahead of the walkout on 23 October the union issued safety advice to the public, and it will do so again if the strike does go ahead on Bonfire Night, Mr Wrack said.
He said he understood the concerns of the public but the union had been left with no choice.
"The alternative is to allow London's firefighters to become doormats for their employers to walk on," he said.
"The long-term safety of Londoners depends on a well-trained, self-confident firefighting force.
"The chairman of the London Fire and Emergency Planning Authority, Brian Coleman, issues calculated insults and says he's relaxed and sacking all of them.
"He and the commissioner, Ron Dobson, want to run the London Fire Brigade as though it were a Victorian mill. They want a frightened and obedient firefighting force. We simply cannot accept that."
Urging the authority to meet representatives and come up with a solution, he said: "There's still nearly two weeks for the London Fire Brigade to get this right."
London Fire Brigade has said changes were needed to make time for "vital training and fire prevention work".
London fire authority chairman Brian Coleman asked: "What sort of union orders its firefighters to go on strike over Bonfire Night?"
"The emergency fire cover did what we expected it to do the first day, and will do so again."