The number of Scotland Yard officers could soon drop to the lowest level since 2002, Sadiq Khan has warned.
The Mayor of London has called for funding to be increased urgently, and will meet Home Secretary Sajid Javid for talks on Tuesday.
Numbers could drop to 26,800 if the force is told to make further savings, Mr Khan claimed.
He said: The causes of violent crime are extremely complex, but there is no doubt it has been made far worse by huge government cuts to the police and youth services.
Even the home secretary has finally admitted that the Met wont be able to tackle violent crime without more funding from the Government.
Now we urgently need to see action to avoid officer numbers falling even further.
Government cuts have led to London losing 3,000 police officers and more than 3,000 PCSOs and 5,000 police staff and Im genuinely concerned about how we keep Londoners safe with officer numbers as low as 26,800.
Ministers need to reverse the £1 billion savings forced on the Met and reverse their cuts on youth services and other preventative services so that we can keep our city safe.
Mr Khan and Mr Javid will discuss the police funding settlement for 2019-20, which the Home Office said is expected in due course.
Scotland Yard has been told to make a further £335 million worth of savings by 2022, Mr Khans office said.
He also dismissed a reported £600 million funding boost for police in England and Wales – saying far more is needed to tackle violent crime.
It was reported that Mr Javid has secured an agreement allowing councils to double the amount they can add to council tax bills for policing.