Mr Khan has said he wants to introduce a wider consultation process before planning permission is granted to build tall buildings.
It comes amid concerns over a 42-storey building in Stratford which has obstructed views of the cathedral from King Henry’s Mound in Richmond Park, nine miles away on the opposite side of the capital.
Existing planning rules stipulate that St Paul’s must be seen against a “clear sky background” but the building, Manhattan Loft Gardens, is now positioned behind the cathedral.
As it stands London boroughs several miles from historic sites are not required to hold public consultations over the impact of new buildings on protected views.
But Mr Khan told the Times he could extend the area in which consultations on the impact on views of St Paul’s should be held.
“Consideration is to be given to including more distant boroughs to prevent this happening again,” he said.
“However, this would currently need government agreement unless the necessary powers are delegated to the mayor, as has been sought.”
Friends of Richmond Park welcomed the proposal and accepted the building in Stratford would not be torn down.
A spokesman told the paper: “We would like the mayor to assure us that there are no other tall buildings in Stratford or elsewhere that are in the protected view line and have been granted permission already or are likely to be before the protection is extended.”