Disturbing video released on Tuesday shows a thug sucker-punching a 65-year-old man in the face in front of his Brooklyn Heights apartment building — but the victim wasn’t phased one bit, saying his attacker was a total coward.

“You’re not tough,” fumed Richard Carey, who is still nursing a pair of cuts around his left eye following the July 6 attack.

“You’re not proving how tough you are…S**t happens…He blindsided me. What does that prove? I could blindside him. It could happen to anybody. It’s very uncool. Get yourself some help. Do whatever you’ve got to do to get some help. Because it’s going to be heat coming down on [you].”

Speaking to The Post outside his building on Tuesday, Carey described how he was coming back from Gallagher’s Steakhouse after finishing up his bi-annual steak dinner with a group of friends he calls “The Carnivore’s Club” when the apparent “knockout game” attack unfolded.

“I turned the corner from Henry onto Joralemon Street,” he recalled. “I looked, there were a couple of people coming towards me. I sort of scoped them out. Didn’t feel any bad vibes, no attitude, no diss…I was like, ‘OK, they’re cool.’ They’re not all clumped together, boisterous or jostling. No words from me to them or them to me. No sneers. No nothing.”

Surveillance footage shows Carey walking down Joralemon Street near the corner of Henry Street when he’s approached by the suspect and three others at around 11:15 p.m.

As the group walks towards him, the suspect can be seen taking a running start as he gears up to land the punch, which broke Carey’s glasses and knocked him over a fence and into some bushes near his building.

“I went to get my keys and the next thing is I’m seeing stars and I was upside down in the shrubs,” Carey said. “Literally I saw horizontal stripes as if on an old analogue TV set on the fritz.”

The video then shows the attacker calmly walking off with the group as Carey struggles to get back on his feet. He was later taken to an area hospital, where he was treated and released.

“It kinda pisses you off,” Carey said. “Good thing is I’m a sturdy guy. He didn’t break my eye socket. He didn’t break my jaw. Either of those were definite possibilities. My jaw was sore for five days afterward.”

Sources told The Post that the attack was believed to be part of the sick “knockout game,” in which criminals try to render their victims unconscious with a single blow.

“We are going through now all of our assault 3’s to see if we can make a connection,” a source said, adding that “a bunch of kids” had committed a string of robberies in the last several weeks near the Barclay Center, including one involving an off-duty cop.

Carey also believed he had fallen victim to the game, which became prominent in 2013.

“I think it’s a repeat of that idiocy of what was going on three years ago,” he said.

Police described the suspect from the video as a black male standing around 5 feet 10 and weighing around 160 pounds. He was last seen wearing a white T-shirt and sneakers.

Carey said the attack has made him more aware of his surroundings.

“I’m more alert,” he said. “I don’t take my eyes off of people. It’s [also] forced me to look at my own prejudices and my own attitudes and all of that stuff.”

The Brooklynite claimed to have seen youngsters acting up in his neighborhood before in the past, but never attacking people randomly in the streets.

“There have been a couple of times when there have been five, ten, fifteen, twenty kids coming from the park, all hyped up, and they’ve been jumping on cars and bouncing balls on people’s houses and just generally being idiot kids,” Carey said.

He noted how the person behind the attack would probably share the video of the incident on social media. In fact, he was hoping for it.

“The kids have got to get the word out that it’s not cool. And if there’s enough visibility, somebody’s going to brag about it,” Carey said. “Somebody’s going to post on social media. And we’ll get the son of a bitch.”

Here’s how to protect yourself from an attack like this: