Vessal said he walked away but returned to the table later and continued a debate with four or five students, when he was "rocked" in the face by an unidentified male. Members of the group, according to the website, called Vessal a "kike" and a "Zionist, racist, baby-killer."
Temple spokesman Ray Betzner said campus police were investigating the incident. He confirmed that a suspect was interviewed but was not charged. The university issued a statement condemning the "disparagement or assault of any person based on religion or nationality."
Members of Temple Students for Justice in Palestine did not return calls seeking comment. In a statement, the group called the assault an "unfortunate incident." The group said the suspect, whom they did not name, was a former student and an acquaintance of group members.
The group, according to its statement, asked Vessal to leave several times before he was "slapped." The group denied using any anti-Semitic slurs.
Vessal did not return requests for comment. His lawyer, Michael Wildes, said he expected that the student group would depict Vessal in "a poor light."
Tipsters may call Temple University police at 215-204-1234.
On Twitter: @JasonNark