"It is the houses of poor people that collapse - and that is no coincidence", he was quoted as saying by local media.
Several people remained missing after the adjacent multi-story structures collapsed on Monday.
"People died for nothing, even though we knew".
But Interior Minister Christophe Castaner had already warned on Monday evening that there was "little chance of finding air pockets" in a pile of rubble stretching 15 metres (50 feet) long.
A third adjoining building partially collapsed on Monday night.
Images taken before the collapse show large cracks in the facade of number 63; a former resident, retired college lecturer Mark Mason, told the Guardian he had been forced to sell his flat in the building to the council in 2012 under a compulsory purchase order after the first storey floor collapsed and chunks of masonry began falling from the building.
The second apartment block, which was in such a bad state that it had been condemned, was boarded up and in theory unoccupied, according to officials.
Fire services said two people who were in the street when the buildings collapsed were treated for minor injuries.
Sophie Dorbeaux meanwhile told AFP she had left the block on Sunday night to stay with her parents because the building's structural problems meant her door, like several others, was not opening or closing properly.
"It could have been me", she added, visibly shaken.
"Nearly 6,000 properties have been identified as at risk" in the city, he said, representing some 44,000 lodgings in lower-class neighbourhoods, calling the situation unacceptable.
Rescue work has been hampered by heavy rain, and evidence suggests the collapse has destabilised neighbouring buildings.
He was not able to say whether squatters had been living there.
Marseille authorities launched a vast upgrade plan for the city centre in 2011. In 2011 the local authorities began a plan to renovate the city centre, but a 2015 government report suggested that 100,000 Marseille residents were living in housing risky to their health or security.