Maggiano’s Little Italy, a diner in the US capital, said it had not realised a group calling itself the National Policy Institute (NPI) was a far-right fringe organisation.
Tila Tequila, an American former reality TV star, tweeted a photo from inside the restaurant where she and others could be seen making Nazi salutes.
Maggiano’s issued a statement saying it would donate its takings from the event on November 18 to the DC office of the Anti-Defamation League.
The NPI, a previously little known organisation, held its annual conference the following day in a nearby conference centre, with around 200 people in attendance.
A video later surfaced online of the NPI’s leader, Richard B. Spencer, addressing the conference with a cry of “Hail Trump, hail our people, hail victory!”
Spencer has previously spoken of his desire to see “peaceful ethnic cleansing” in the US, and the country to become “a home for Europeans”.
US political magazine The Atlantic reported that Spencer told delegates at the meeting: “America was until this past generation a white country designed for ourselves and our posterity.
“It is our creation, it is our inheritance, and it belongs to us.”
The speech has been widely reported across North America as an indication of racist groups being ‘emboldened’ by the election of Donald Trump.
Tequila, a controversial social media personality with a history of making provocative comments, later defended her actions as “trolling”.
“We were doing the Roman salute,” she told an online magazine. “We were just trolling around. Everyone was making such a big deal about this event, and all these people were Nazis or whatever.”
She was later suspended from Twitter.
White nationalists and other racist organisations in the US have greeted the recent election of Donald Trump with enthusiasm.
The New York Times reported one NPI delegate as saying Trump’s victory had given the so-called alt-right “breathing room”.
Trump has denied he has connections to the far-right. But his views on immigration and foreign policy have “captivated members of the movement”, the Times said.