The teenager was the 57th person to be questioned in connection with Wednesday's riot during which a fire extinguisher was launched from the roof of Millbank Tower after protesters stormed the Conservative Party headquarters.
A student at Anglia Ruskin University, Cambridge, has already been questioned in connection with the incident and released on bail. The 23-year-old, originally from Reading, Berkshire, was held at Parkside police station in Cambridge.
A Met spokesman said the 17-year-old arrested on suspicion of violent disorder had been bailed to a date in mid-February pending further inquiries.
Police Federation representatives have called for the person who flung the empty metal fire extinguisher from Millbank Tower to be charged with attempted murder. Senior officers said it narrowly missed injuring two territorial support group officers.
The incident was one of the defining moments of the four-hour stand-off after a breakaway group of students attacked the Millbank office complex. Up to 50 demonstrators smashed windows, discharged fire extinguishers and threw debris from the roof of the building.
But hundreds of others gathered in a forecourt below booed the culprit and shouted to others to stop damaging the building and throwing missiles.
Some student activists have begun fighting a rearguard action amid widespread condemnation of the violence and fears of further trouble on November 24 – the day it is widely believed that Ministers will vote on the tuition fees rise in the Commons.
Clare Solomon, president of the University of London Union, claimed protesters were "goaded and provoked" by police.
Meanwhile, senior officials at the National Union of Students wrote to staff at the Millbank Tower complex expressing "deep regret".