Cheryl Boone Isaacs, president of the Academy of Motion Picture Arts and Sciences, told the 165 Oscar-nominated actors and film makers there was a "struggle globally today over artistic freedom that feels more urgent than at any time since the 1950s," an apparent reference to the anti-communist blacklists of some in the movie industry at the time.
Speaking at a luncheon in Beverly Hills for the 2017 nominees, Isaacs noted that there were "some empty chairs in this room, which has made Academy artists activists."
Iranian director Asghar Farhadi and actress Taraneh Alidoosti, who stars in his foreign-language nominated film "The Salesman," said last week they would boycott the February 26 Academy Awards to protest President Donald Trump's travel restrictions on Iranians and six other Muslim-majority countries.
Other Oscar nominees who expect to find difficulty travelling to Los Angeles for the ceremony include those behind documentary The White Helmets about civilian Syrian rescue workers.
Isaacs did not directly mention the travel restrictions, but she said: "America should always be not a barrier but a beacon. We stand up to those who would try and limit our freedom of expression.
"When we speak out against those who try and put up barriers, we reinforce this important truth - that all artists around the world are connected by a powerful bond, one that speaks to our creativity and common humanity," she said, to loud applause.
Isaacs' address followed fiery speeches at recent awards shows and rallies by celebrities ranging from Meryl Streep to Madonna and Ellen DeGeneres condemning the travel ban, supporting civil and women's rights, and criticising Trump's behaviour.
