The four men, aged between 19 and 23, were held on Monday on suspicion of the commission, preparation or instigation of an act of terror, while a fifth man, 19, was arrested on suspicion of encouraging terrorism.
The raids in Manchester, Peterborough and north London on Monday were part of a pre-planned operation and were not linked to either the London Bridge terror attack last month or the New Year's Eve, the Metropolitan Police said.
A Met statement said: "Officers from the Met's Counter Terrorism Command along with colleagues from the Counter Terrorism Policing North West (CTPNW) unit and the Eastern Region Special Operations Unit (ERSOU) CTP have arrested five men on suspicion of terrorism offences.
"The men were arrested on the morning of Monday, 30 December at addresses in north London, Manchester and the Peterborough areas.
"All five men remain in police custody at this time."
Those arrested for plotting a terror attack included a 21 year old in Manchester, a 19 year old in Peterborough and two men, aged 22 and 23, in north London.
The teenager suspected of encouraging terrorism was arrested in Peterborough.
Officers continue to search addresses in each area.
The force added there is not believed to be any imminent threat to the public.