Sander described the incident at a restaurant in Virginia on Friday in a post on Twitter.
"Last night I was told by the owner of Red Hen in Lexington, VA to leave because I work for @POTUS and I politely left," Sanders tweeted. "Her actions say far more about her than about me. I always do my best to treat people, including those I disagree with, respectfully and will continue to do so."
The restaurant's Facebook page included posts supporting Sanders and criticizing the restaurant in Lexington, a town of 7,000 that is 190 miles southwest of Washington, D.C. In the 2016 election, Hillary Clinton received 61.8 percent of the vote compared with Trump's 31.3 percent.
Restaurant manager Stephanie Wilkinson told The Washington Post she received a call from her chef around 8 p.m. that the staff was concerned after Sanders arrived with her husband and six others in the 26-seat restaurant. They had been served cheese plates and the main course was being prepared.
"I'm not a huge fan of confrontation,"Wilkinson, who then went to the restaurant, said. "I have a business, and I want the business to thrive. This feels like the moment in our democracy when people have to make uncomfortable actions and decisions to uphold their morals."
Wilkinson said she told Sanders: "I explained that the restaurant has certain standards that I feel it has to uphold, such as honesty, and compassion, and cooperation. I said, 'I'd like to ask you to leave.' "
Sanders's response, according to Wilkinson, was: "That's fine. I'll go."
Her father, former Arkansas Gov. Mike Huckabee, blasted the owners of Red Hen, posting on Twitter: "Bigotry. On the menu at Red Hen Restaurant in Lexington VA. Or you can ask for the "Hate Plate". And appetizers are "small plates for small minds."
A restaurant in Washington, D.C., also named the Red Hen said that it has no affiliation with the restaurant in Virginia.
"Good morning! @PressSec went to the unaffiliated @RedHenLex last night, not to our DC-based restaurant," the Washington restaurant posted on Twitter.
Walter Shaub, the federal government's former top ethics watchdog, said Sanders' decision to tweet about being kicked out of a Virginia restaurant violated ethics laws.
"Sarah, I know you don't care even a tiny little bit about the ethics rules, but using your official account for this is a clear violation of 5 CFR 2635.702(a)," Shaub tweeted Saturday, referencing the law that states government employees cannot use public office for private gain.
In addition, he said the tweet also violated the endorsements ban since Sanders's tweet was "an obvious corollary for discouraging patronage."