"Disney should be ashamed of themselves for resorting to tired tactics of gender-shaming and bullying," Carteris said in a statement, published by Deadline.
"Actors must be compensated for their work according to their contracts. Scarlett Johansson is shining a white-hot spotlight on the improper shifts in compensation that companies are attempting to slip by talent as distribution models change. Nobody in any field of work should fall victim to surprise reductions in expected compensation. It is unreasonable and unjust. Disney and other content companies are doing very well and can certainly live up to their obligations to compensate the performers whose art and artistry are responsible for the corporation's profits."
"Additionally, we are deeply concerned by the gendered tone of Disney's criticism of Ms Johansson. Women are not 'callous' when they stand up and fight for fair pay – they are leaders and champions for economic justice. Women have been victimised by pay inequity for decades, and they have been further victimised by comments like those in Disney's press statements. These sorts of attacks have no place in our society and SAG-AFTRA will continue to defend our members from all forms of bias."
In their statement released publicly after Johansson's filing, a Disney spokesperson said there was "no merit whatsoever" to the lawsuit.
"Disney has fully complied with Ms Johansson's contract and furthermore, the release of Black Widow on Disney+ with Premier Access has significantly enhanced her ability to earn additional compensation on top of the $20m she has received to date," the spokesperson said.
Black Widow has grossed more than $350m worldwide at the box office since it was released in cinemas a month ago.