The video that recently surfaced online of several teenagers pummeling another group of boys on a pier at Squantum Point Park is “not a reflection of what Quincy is about,’’ Mayor Thomas P. Koch said Thursday.

His comments came one day after State Police announced that seven teenage boys face a slew of charges in the July 31 attack, including kidnapping and assault and battery. The attack was captured on video and posted to Instagram under the hashtag “QuincyVsMilton.’’ As of Thursday morning, it had received more than 41,000 views.

State Police have not released the hometowns of the five alleged victims but said Milton police assisted in the investigation. Six of the seven alleged attackers — ages 15 to 17 — are from Quincy. The seventh, age 14, is from Kingston.

State Police say investigators are working to determine what motivated the attack, which was launched after the victims were lined up against a railing. The teens face kidnapping charges because they initially refused to let the other boys leave the pier, police said.

David Procopio, a State Police spokesman, said the evidence suggests that the suspects and victims had “no prior knowledge of each other.’’

“Whether there was any underlying tension between the assailants and other groups is still part of the investigation,’’ he said.

The brief video opens with three youths standing by a railing on the pier, as the attackers slowly advance toward them. Someone from the group of suspects is heard saying, “Stop crying, [expletive].’’ The assailants repeatedly use the racial slur as they shout at the victims, most of whom appear to be white. The attackers appear to be people of color, but Procopio said the clash did not appear to be racially motivated.

“At this point the evidence does not suggest that, but the investigation is ongoing,’’ he said. “And if that is determined to have played a role, the charges will be amended to reflect that.’’

As the video progresses, one assailant can be heard shouting “start [expletive] walking,’’ and two of the victims are thrown to the ground and repeatedly punched and kicked.

The attack stops as a friend of one of the victims shouts, “He’s not doing anything.’’ The friend also appears to say that he didn’t spit or spill “on anyone,’’ though it’s not clear what he’s referring to.

Koch, the Quincy mayor, strongly condemned the assault.

“That behavior is unacceptable and certainly will not be tolerated in Quincy,’’ Koch said. “There’s so much more of an emotional reaction because you see it [on video]. It’s disgusting to look at.’’

Koch said he has received no indication that a rivalry between Quincy and Milton touched off the assault, but he conceded that teenagers in the two communities do not always see eye to eye.

“Historically, there’s always been that rub,’’ Koch said. “That’s probably gone on for generations. I don’t know that that’s the case here.’’

Koch said youths sometimes gather at the pier to jump into the water but said he was not aware of any previous violence. A Quincy police spokesman said the area is safe and that officers have received “very few calls in that location.’’

Koch said he was concerned about how the city might be perceived in the aftermath of the video, which has been met with outrage online.

“There’s a great sense of pride here, and to have something like that on social media, it takes away from all the good work that’s being done in so many ways,’’ he said. “For people to judge the community on one incident, that’s unfortunate. It’s not a reflection of what Quincy is about. This is an isolated incident that will not be tolerated.’’

Milton Town Moderator Robert Hiss also downplayed the notion of a rivalry between the municipalities, in an e-mail. He said he does not know anyone involved in the incident.

“If there is any Quincy-Milton rivalry I’m unaware of it,’’ Hiss wrote. “My youngest son sailed in Quincy at the Squantum Yacht club for years and he had a great experience with kids from Milton and Quincy mixing together swimmingly, so to speak.’’

Travis Andersen can be reached at travis.andersen@globe.com. Follow him on Twitter @TAGlobe.