One neighbor shot a video of the beating and distributed it to family and a television station. Another video was shot from the other side of the street and posted to YouTube.
Relatives watched the video and told CNN that the teen is Tariq Khdeir. Relatives released pictures of the bruised teenager with swelling on his lips and nose.
The men delivered more than 20 blows to the youth over a period of two minutes. He did not appear to be struggling and police carried away his limp body afterward.
Both videos start after the incident began, and it's not clear why Khdeir was attacked.
'That should not happen'
Mark Regev, spokesman for Israeli Prime Minister Benjamin Netanyahu, said he had seen the videos on CNN.
"I think people who have that video should take it straight to the Israeli police," he said. "There is a separate department in our Ministry of Justice who will investigate that sort of thing."
Regev said he did not know the details of this case. "That should not happen," he said. "Obviously, it is forbidden under Israeli law to beat up a suspect who is in handcuffs."
"It's attempted murder," Suha Abu Khdeir said of her son's beating.
Calls for U.S. to intervene
Khdeir's father told CNN that a U.S. consular officer visited the teen in a Israeli detention center in Jerusalem. The officer told Khdeir's father that the teen does not remember much of what happened during his arrest.
The officer passed on a note from Tariq in which he said he was OK and told his parents not to worry about him, according to the uncle who is in regular contact with the parents.
U.S. State Department spokeswoman Jen Psaki called the reports "troubling" and called for a "speedy, transparent and credible investigation and full accountability for any excessive use of force."
The Council on American-Islamic Relations urged the United States to help free the teen.
"It is the duty of American officials to intervene and secure the release of an American citizen who was so viciously attacked," said Hassan Shibly, executive director of CAIR-Florida.
Khdeir is expected to appear at the Jerusalem magistrate court at 11 a.m. Sunday (4 a.m. ET), according to his father.
His cousin, Mohammed Abu Khedair, who was abducted and killed in Jerusalem this week, died from being burned alive and hit on the head with a blunt object, according to Palestinian General Prosecutor Mohammed al-Auwewy, citing a medical autopsy.
Al-Auwewy said the autopsy discovered traces of smoke inside the lungs of the 16-year-old, indicating that it was inhaled while the fire was burning.
After the teen's funeral on Friday, more than 60 people were injured in clashes with Israeli security forces in parts of Jerusalem, according to the Palestinian Medical Relief Society, a group that said it was involved in evacuating injured Palestinians. It said the injuries mostly involved rubber bullets fired at the upper body and chest.