“We’ll continue to campaign against it and rule nothing out - depending on the final decision we may consider industrial action.”
Labour’s London fire spokesman Navin Shah accused Mr Johnson of ignoring the fire authority against the wishes of Londoners.
“The Mayor needs to think again and look at reallocating resources from the wider Greater London Authority budget. This will keep our fire stations open and protect the safety and security of Londoners,” he said.
The Greens’ Darren Johnson called on the Mayor to rethink his spending plans as the authority had sent a “clear and decisive” message the closures were unacceptable.
Lib Dems suggested that if the Mayor pushed through the changes as planned he was responsible for the safety of Londoners.
Assembly member Stephen Knight said: “The consequences for the safety of Londoners will be squarely on his shoulders.”
Brigade chiefs are planning the biggest shake-up in its 146-year history and last year offered all 5,727 firefighters and 1,000 civilian staff the chance to take voluntary redundancy - with a £10,000 “golden goodbye” to entice civilians to leave.
Fire deaths have fallen from 81 in 2001 to 55 in 2011.