Police said this week that they have assessed hundreds of online postings and calls to 911 and pressed the public to continue to report any suspicious activity.
"All threats against members of the NYPD are taken seriously and are investigated immediately to determine the credibility and origin of the information," authorities said Wednesday.
The two latest arrests were announced Friday.
In one case, a man walked into the 28th precinct, approached a desk and harassed and threatened officers before being apprehended, police said. He faces charges of assault on a police officer, resisting arrest, obstructing government administration, criminal trespassing, disorderly conduct and harassment.
In another case, a man noticed an off-duty officer on the street wearing part of his uniform under his jacket, police said. Authorities said the man verbally threatened the officer and made a firearm gesture with his hands. The off-duty officer called 911, and the suspect fled. He was later found sleeping in the stairwell of a building nearby.
The arrests come as an investigation continues into Ismaaiyl Brinsley, the 28-year-old who police say shot Officers Wenjian Liu and Rafael Ramos in Brooklyn.
Hours before the officers were shot, Brinsley apparently posted on his Instagram account: "I'm putting wings on pigs today ... they take one of ours, let's take two of theirs." Brinsley committed suicide after shooting the officers, police said.
Among the other arrests this week, a 26-year-old allegedly posted pictures of weapons on his Facebook page along with threats to kill police officers, NYPD spokeswoman Sophia Mason said.
The man's Facebook post indicated that he wanted to kill two police officers, NYPD Detective Annette Markowski said. He was charged with making terroristic threats.
A 41-year-old also was arrested Wednesday on charges of aggravated harassment and making terroristic threats after he allegedly called into the 84th precinct -- where Liu and Ramos had been stationed -- and, requesting to speak to Ramos, asked whether the bullets had been removed from the dead officer's head so "he could kill more cops," Mason said.
Of the arrests, police said, at least three stemmed from postings made on social media, and at least two came from misdemeanor charges of false report incident, in which the suspects allegedly called 911 reporting threats made by a third party that were later debunked.
One arrest was made after the suspect phoned in a direct threat to 911.
And on Wednesday, a man was arrested on weapons, drug and harassment charges after he was overheard threatening to kill cops while talking on his cell phone inside a bank in Queens, according to the NYPD.
That man is accused of saying on the phone that he was going to kill a cop, and that Brinsley should have killed white police officers, according to a criminal complaint filed in court. The complaint says that when police interviewed the suspect, he elaborated that two white officers should have been killed "if the guy really wanted to send a message."
In a tweet Thursday, Mayor Bill de Blasio thanked the police department and the civilian who saw something suspicious and acted:
"Thank you to the NYPD officers who today arrested a man who threatened to kill cops, and to the good Samaritan who provided key information."