Although visa problems forced the singer to pull out at the last minute, the event will still go ahead with equal headliner Atif Aslam.
"Disappointed and enraged to inform everyone that I'm not coming to London. Hard to believe that except my visa, not a single visa for my group was done," Nigam posted, 24 hours before the planned gig.
The star went on to clarify: "Never happened in 20 years of overseas travel. Don't know whom to blame. Our entire team's time and repute has been wasted.
"Only if the show is postponed now to another date, would we be vindicated. Prayers everyone."
Nigam had also posted last week that he would not be playing in London, before telling fans that the gig was back on.
Denying reports that Dhamaka had been cancelled, organiser Naz Choudhury has confirmed that the concert will still take place with a longer set from Pakistani singer Aslam.
Dance troupe Bolly-Flex, previously seen on Sky1's Got to Dance, will also be performing.
Dhamaka comes to London for one night only on Sunday, April 22.
> Read Digital Spy's interview with Sonu Nigam
Watch a video-message from Aslam about the concert below: