The protesters are upset at Nonmacher's Barbecue on South Mason Rd. because of a poster on display at the business.
The poster shows two dozen men lynching an Iranian man and has a caption that reads "Let's play cowboys and Iranians."
The demonstrators say its racist and they want it taken down.
The owner says it was taken during the Iran hostage crisis and has been there more than 30 years.
The Public Affairs Alliance of Iranian Americans also spoke out against the poster. They wrote a letter to the owner on Friday, expressing their concern over the image.
"While we believe it was not your intent to single out an entire ethnicity, we feel that the poster could be easily misinterpreted by some and encourage racisms. As we are sure you can appreciate, such unintended consequences are not only un-American but also damaging to Iranian Americans and those living in Iran who are fighting for Democratic reform," the letter read. "To avoid such misunderstandings, we respectfully request that you take down the poster in respect of differentiating between the government and the peoples of Iran."
Not everyone there Saturday protested the business.
Some showed up and spoke out in support of the business and its owner.
There was also a continuous customer line to enter the establishment. The owner said he believes it was his restaurant's busiest day in history.