The Sex and the City star, who married wife Christine Marinoni in 2012, urged members of the Lesbian, Gay, Bisexual, Transgender (LGBT) community to stand together.

"Hello brothers. Hello sisters. Hello siblings who reject the gender binary," she said at the protest event on Saturday. "As LGBT people, we know how important coming out is, but I would argue that our coming out has never been more important than it is right now.

"We need to come out not just as queer, but as people who know all too well what it feels like to be put in a box that says 'other, less than, easy target if you're looking for someone to bully, harass, discriminate against, demonise, beat up, even kill'."

Nixon used her speech to slam new U.S. Vice President Mike Pence for passing anti-LGBT laws in his home state of Indiana.

"We don't know yet what Donald Trump has in store for us, and chances are he doesn't either," she continued. "He poses as our ally... but he chooses Mike Pence, the poster boy for anti-LGBT rhetoric, legislation and conversion therapy, as his vice president."

Ironically, the actress recently played former First Lady Nancy Reagan in U.S. TV movie Killing Reagan, and she admits she was never a fan of Republican Ronald Reagan or his wife - and that may have helped her nail the character.

"In some ways maybe it's harder to play someone you actually worship because you feel the distance between you and them is so great," she told Entertainment Tonight. "There's liking someone and then there's disapproving of them. Let's say you're playing a character that you disapprove of - one of the dangers is that you condescend to that character and you do a more caricature-y version of them, because you don't respect them.

"There was no question in my mind that Nancy Reagan worked very hard in her life and tried to be the absolute best person by her standards that she could be. There were all these tragic, painful things that happened early in her life that set her on a particular path."

Nixon has also portrayed First Lady Eleanor Roosevelt in the 2005 TV movie Warm Springs.