The suspect Sayfullo Saipov, a national of Uzbekistan, was shot by police following the attack near the World Trade Centre site on Tuesday but is expected to recover from his wounds.
Authorities found a note referring to Isis inside the rented pickup truck he used to plough into cyclists and pedestrians, Mr Cuomo said. It claims in Arabic that the 29-year-old committed the atrocity in the name of Isis.
“He was associated with Isis and he was radicalised domestically,” Mr Cuomo said on CNN. “It's not the first time. It’s a global phenomenon now.”
New York Police Department Deputy Commissioner John Miller said Mr Saipov had closely followed Isis instructions from social media and had been planning it for a number of weeks.
Eleven people were also injured in the attack when Mr Saipov hurtled down a cycle lane before crashing into a school bus.
He then jumped out of the van brandishing what turned out to be a pellet and paint gun, and was shot in the abdomen while trying to flee the scene.
Mayor Bill de Blasio called the attack — the deadliest in the city since 9/11 — “a cowardly act of terror.”
Among those killed were five Argentinian friends who were on holiday in New York to celebrate the 30th anniversary of their graduation, the BBC reported.
They were named as Hernan Diego Mendoza, Diego Enrique Angelini, Alejandro Damian Pagnucco, Ariel Erlij and Hernan Ferrucci.