Jessica Chastain, Elizabeth Banks and Emma Watson were among those to tweet their support.
Watson said: "O Jennifer Lawrence I love you so". Banks declared: "I love Jennifer Lawrence", while Chastain exclaimed: "Yessssssss! Get it girl."
Last week, Meryl Streep - one of Hollywood's most successful actors - spoke out about sexism in the film industry, saying that even she receives less pay than male co-stars.
And at a global symposium on gender in the media, Oscar-winning actress Geena Davis called for more women on screen and more challenging female roles in TV and film.
"We are unwittingly training generation after generation to see men and women as unequal," said Davis.