Adams shared on Twitter that his heart went out to all the families of the victims and announced those who purchased tickets would receive a refund.
"In solidarity with the victims of the mass murder, yesterday in Christchurch, NZ, our concert scheduled for Sunday at Hagley Park will not go ahead."
Hagley Park is located a short distance from the Masjid Al Noor mosque where 41 people were killed in the terror attack. Seven others died at a mosque in Linwood, while one other victim later died in hospital.
Alvarez said when the tragedy was unfolding all of the staff working to set up the site for the concert were evacuated.
He could not say what those staff witnessed or heard but said sent his condolences out to every person affected by the senseless act, describing it as worse than something out of a movie scene because of the "real people" impacted.
"It's disgusting," Alvarez said.
Alvarez said Adams really liked New Zealand and maybe one day in the future he could return to Christchurch to perform for the city that had suffered so much.
"I'm always travelling the world. Everywhere I go I never feel safer than I do in New Zealand."