The woman, in her 40s, whose identity was not immediately known, was seated with friend at the French bistro, at 128 Smith St., at about 6:30 p.m. The man and another woman were seated at a neighboring table.
A verbal dispute broke out between the two tables, and the man asked management to kick the two woman out of the restaurant, according to general manager Jonas Leon. Though he declined to eject the two women, Leon moved the male and female couple to a different table, he said.
"It was really hard because the restaurant was packed, packed, packed," he said.
However the man remained belligerent and eventually left the restaurant still complaining in a "really aggressive way," Leon said.
But two minutes later, the man rushed back into Bar Tabac, "almost running," and pushed his way to the woman whom he had been arguing with and "just punched her," Leon said.
"It was because of politics," he said. "The guy who punched the girl was pro-Trump for sure."
Boerum Hill resident Katie Nave Freeman was dining at the restaurant with a friend and their young daughters when she saw people shoving and yelling, "call 911!" In the next instant, "everyone was frozen and the woman in the back corner of the restaurant had her hands over her face," she said via email to DNAinfo.
"The woman was extremely (and understandably) shaken," Freeman said. "She grabbed me, sobbed and held the left side of her face in her hand."
Freeman spoke to the victim after the incident and learned that "the two women were discussing Trump and their disappointment in the election results and the man got angry," she said.
The man was escorted out of the restaurant and the staff alerted authorities. But when police arrived, the man had already left.
Bar Tabac posted a statement on Facebook Monday morning.
A police spokeswoman confirmed that an unknown perpetrator had punched a woman on the left side of her face at Bar Tabac on Saturday at about 6:50 p.m., but could not confirm the subject of the dispute. No arrests have been made in the case.
This is not the first incident of violence that Trump's win has sparked in the city. A 23-year-old woman shoved a 74-year-old man last week in a fight over the bitter 2016 election.
"Day after day, this will happen more and more," Leon said. "I hope not, but you know now every American is really sensitive about the subject."