Farhadi, 44, did not attend the ceremony because he said that the conditions that would be attached to a potential entry visa were unacceptable.
Iranian astronaut Anousheh Ansari accepted the award on behalf of director Asghar Farhadi.
"I'm sorry I'm not with you tonight," Ansari read in a statement. "My absence is out of respect for the people of my country and those of other six nations who have been disrespected by the inhumane law that bans entry of immigrants to the U.S."
"Dividing the world into 'us' and 'enemies' categories creates fear," Ansari continued in Farhadi's statement, which concluded with a passionate defense of the power of film to create empathy "between us and others, an empathy that we need today."
Firouz Naderi, a former NASA director, and an Iranian stood beside Ansari as she read Farhadi's words.
Backstage, Naderi said that Farhadi could have chosen any number of prominent Iranians to represent him at the Oscars, but that he chose two scientists who focus on space because "if you go away from the earth and look back at the earth you don't see the borders and the lines."
The Salesman premiered at Cannes last May, where it won best actor for Shahab Hosseini and best screenplay for Farhadi – despite moderate notices from critics. The film follows a couple in Tehran involved in an amateur dramatic production of Arthur Miller’s The Salesman, who are forced to move apartments following an earthquake. But the flat into which they move has an unhappy history, compounded by an unwelcome intruder.
Farhadi won Iran’s first Oscar for his film A Separation in 2012. This second award puts him in an elite category of double-winners in the category, including Federico Fellini and Ingmar Bergman.
The ban not only led to Farhadi announcing that he would not attend the awards in protest of the ban, targeted toward predominantly Muslim countries, including Iran but also to an unprecedented show of solidary between the six nominated directors in the foreign language category. Two days before the Oscars, the six directors issued a joint statement decrying the climate of "fanaticism" in the United States. They said that no matter who won, the award would be dedicated to people working to foster "unity and understanding."