Ariana Grande has stepped up to defend Little Women star Florence Pugh after she became the target of mean trolls by going public with her new romance.

The 24-year-old actress took to social media earlier this week to address the abuse she has been subjected to since wishing her actor boyfriend, Zach Braff, a happy 45th birthday.

The online meanies took objection to the age gap between the pair and launched into Pugh.

"On Monday, I posted a photo in honour of Zach's birthday and I wrote a birthday message underneath," she responded in a video. "Within about eight minutes of the photo being posted, I had about 70 per cent of the comments hurling abuse and being horrid - basically bullying someone on my page. It is the first time in my entire Instagram life that I've had to turn off the comments on my page.

"I've never been an Instagram page that encourages that (sic). I've never been an Instagram page that likes that toxic vibe... I do not need you to tell me who I should and should not love and I would never in my life tell anyone who they can and cannot love. It is not your place."

And now Ariana has saluted the star for standing up for herself: "Oh I love and appreciate you so much," the singer wrote on her Instagram page.

Posting Florence's video response to the trolls, Grande added: "Sharing special, personal life things on the internet can be truly traumatic. I just wanted to share this and let you know how perfectly u expressed this and how appreciated you are for doing so (sic)."