A video showing a dispute between a Republican Party videographer and a cab driver for Senate candidate Elizabeth Warren made the rounds on the Internet Monday, with state Republicans calling the incident “unacceptable” and Ms. Warren’s campaign denouncing the confrontation and saying the driver was not affiliated with the campaign.

The 44-second video, posted on YouTube, shows footage of Ms. Warren and her staff getting into a Martha’s Vineyard Taxi vehicle in Oak Bluffs on Sunday. A man in a baseball cap, who appears to be the cab driver, puts his hand on the video camera and apparently knocks it to the ground. As the man went to the driver’s side of the vehicle, he turned back around and confronted the videographer, saying “Dude, get out of my face or I’m going to call the police.” The unidentified cameraman responded by saying that it was a public event. The two argued back and forth, and the driver ended by saying “you are messing with the wrong people.” Ms. Warren appeared to be in the vehicle while the incident occurred.

Campaign trackers are often employed to record candidates’ activities for opposing groups.

State Republican party officials charged that the cab driver was a Warren campaign aide, but a Warren spokesman denied that.

“The person featured in the video was not a member of the Elizabeth Warren for Massachusetts staff,” Warren campaign communications director Julie Edwards said in a statement. “He is a cab driver. Elizabeth did not see what happened. The photographer has a right to film in public locations, and the campaign had allowed him to film the entirety of Elizabeth’s event. The confrontation was wrong.”

An employee at Martha’s Vineyard Taxi, reached by telephone, had no comment.

Nate Little, the executive director of the Massachusetts Republican Party, said in a statement: “Yesterday on Martha’s Vineyard, a campaign aide for Elizabeth Warren physically assaulted and threatened an employee of the Massachusetts Republican Party. In addition to knocking the camera from the employee’s hand, the individual also threw a punch. This type of behavior is completely unacceptable and has no place in our public discourse. Despite witnessing this assault first-hand, Professor Warren took no action and allowed it to continue. Professor Warren needs to address this situation and ensure that it doesn’t happen again.”