Discussing her friend, Camila revealed that Ariana was "shaken up" after the attack at her concert which tragically killed 22 and left many injured.
The 20-year-old added: "I spoke to her after it happened. I am so sorry.
"She was shaken up, what else can you say?"
Camila has praised her friend Ariana in light of her upcoming concert
Ariana will return to Manchester on Sunday for a charity gig in honour of the victims
It's horrible that it takes something like that for people to come together like that, but I am super proud of her
"We were just talking about the concert in the car and it's horrible that it takes something like that for people to come together like that, but I am super proud of her," Camila added.
It comes after Ariana confirmed the charity concert would take place on Sunday, June 4 and will feature a host of stars.
Justin Beiber, Take That, Katy Perry and Coldplay are among those who will join the pop star on the line-up.
A wealth of artists will join Ariana on Sunday Mourning for Manchester: The world pays tribute Thu, May 25, 2017
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Makeshift memorials and tributes to victims of the deadly attack at an Ariana Grande concert.
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Britain's Queen Elizabeth visits the Royal Manchester Children's Hospital in Manchester
Fans who were at Ariana's concert last week have been offered free tickets as long as they register their interest on Ticketmaster before 4pm today.
The event will be shown on BBC television on the day and ITV have confirmed they will move the Britain's Got Talent final to Sunday out of respect for the victims.