In July, the new government asked Khan to more than double the number of new homes being built in the capital each year.
He has been set a new target of 80,000 homes; about 35,000 were built last year.
But the Conservatives say the new figure is less than London needs and less than the target they had set the mayor for home-building in the capital each year.
In his speech at the Centre for London, Khan said: “In short, investment in building homes people can afford will lead to the growth we need.
“That’s why, as well as doing everything I can from City Hall, I’ll continue to make the case for the national investment we need – for the benefit of London and the whole country.
“If there was ever a time for more public investment in housing, then it’s now. And if there was ever a place to show how government still has the capacity to improve the condition of people’s lives, then it’s housing.”