Four women in Southern California were asked to prove they were legal residents by a waiter in a restaurant.
Managers of Saint Marc, in Huntington Beach, later apologised and said they had fired the staff member.
The original Facebook post about the incident has been shared more than 1,000 times and gained hundreds of comments.
But the women have also received a backlash from people dubbing the story “fake news”.
Diana Carrillo, who has Mexican ancestry, told the BBC: “I’ve never faced discrimination like this in the past. The four of us who went to the restaurant were all born in the United States.”
The incident happened when they visited the restaurant on 11 March.
Ms Carrillo said: “As soon as I sat down, the waiter approached the table and without welcoming us, asked me for my proof of residency.
“I just handed it over to him. I didn’t know what to say. I had no words. I felt paralysed literally for a few moments, just in a complete state of shock.”
She said the waiter then asked her friends and sister the same thing, adding: “I have to make sure you’re from here before I serve you.”
US President Donald Trump was elected in November amid tough rhetoric on immigration and has pledged to build a wall along the Mexican border.
“I think a lot of people think they have the power to discriminate against people more openly than before,” Ms Carrillo said.
“I woke up this morning to a lot of comments stating this is fake news, that this didn’t happen. Unfortunately it did happen and it happened to me and three other people. We have to bring awareness to racism and address this.”
The women say they told management immediately, who offered to move them to a different section but they had already decided to leave.
The Washington Post reports that management contacted the women on Monday, offering a VIP experience at the restaurant and pledging to donate 10% of the weekend’s proceeds to a non-profit organisation of the group’s choice.
They declined the meal but asked the donation be made to Orange County Immigrant Youth United.
Kent Bearden, senior director of operations at Saint Marc, confirmed to the newspaper that the waiter in question was fired and said that that employee’s actions “are something that you can’t control”.
“That individual did not treat a table of guests to the expectations that we set forth in that company policy, and that caused him to be terminated,” he said.
Ms Carrillo told the BBC she was happy with the restaurant’s initial handling of the incident, but has been disappointed that an official apology has since been removed from the restaurant’s social media page.
US waiter fired after asking diners for proof of residency