She tweeted: "Ari the world could only dream of being as compassionate and gentle as you. And since ur being, as always, so classy and nice, allow me the honour of telling them to shut the f**k up. (sic)"
The No Tears Left to Cry hitmaker thanked Halsey for her support, saying she loves her "very much".
Ariana subsequently tweeted: "Everything I feel is valid and safe. Everything I do is genuine and honest. There is no right or wrong during this period. Sending you all a s**t ton of love. Peace (sic)."
The exchange came after Ariana shared a heartfelt message about her ex-boyfriend Mac Miller on Thanksgiving.
The singer - who has recently been dealing with the tragic death of the rapper in September, and the end of her engagement to comedian Pete Davidson - confessed that her ex, Mac, is very much missed.
Ariana shared a photo of herself with Mac - who died from an accidental drug overdose - during the annual holiday in 2017 on her Instagram Story and she captioned the image: "You're v missed. (sic)"