Manning, 38, formerly Bradley Manning, was convicted in 2013 by a court-martial of leaking classified material to Wikileaks, the group established by Julian Assange.
The trial heard up to 750,000 documents and other materials were leaked by the former army intelligence officer while stationed in Iraq.
Manning was sentenced to 35 years in jail, and served seven of them, a lot of the time in solitary confinement, before the sentence was commuted by Barack Obama in one of his final acts as president.
The US had also wanted to pursue Mr Assange, an Australian citizen, under the 1917 Espionage Act, and he spent almost four years in London’s high-security Belmarsh Jail after being removed from London’s Ecuadorian embassy, where he had been taking refuge for seven years.
With the involvement of the Australian government, a deal was agreed in 2024 in which he pleaded guilty to one count of conspiracy to unlawfully obtain and disseminate classified national defence information. He then moved back to Australia.
A spokesperson for the New York Police Department said they could not immediately confirm the number or identity of those arrested on Monday.