Federal officers entered Representative Jerry Nadler’s office in Lower Manhattan on Wednesday and handcuffed and briefly detained one of his aides. The confrontation happened shortly after the aide observed federal agents detaining migrants in a public hallway outside an immigration courtroom in the same building as the congressman’s office.

The episode was recorded by someone who was sitting in Mr. Nadler’s office. In the video, an officer with the Federal Protective Service, part of the Department of Homeland Security, is shown demanding access to a private area inside the office. The video was obtained by Gothamist, which earlier reported the confrontation.

“You’re harboring rioters in the office,” the federal agent, whose name tag and officer number are not visible in the video, says to a member of Mr. Nadler’s staff.

There were no riots reported on Wednesday at the federal building on Varick Street, though protesters and immigrant rights advocates gathered inside and outside the building earlier in the day. The immigration court is on the fifth floor and Mr. Nadler’s office is on the sixth.

The agents entered Mr. Nadler’s office because they had been told that protesters were there and were concerned for the safety of his staff members, according to a statement on Saturday from the Department of Homeland Security.

When they arrived, “one individual became verbally confrontational and physically blocked access to the office,” the statement said. That person, an aide to the congressman, was detained so the officers could complete their safety check, according to the statement.