The man charged with fatally mowing down a construction worker during a road-rage scuffle on the Upper East Side told cops he feared for his family’s safety — and that he had only meant to disarm the other motorist, not mortally wound him, sources told The Post Thursday.

Andre Mosby, 26, also allegedly claimed he only struck 54-year-old Roberto Velez Alvarez with his 2014 Volkswagen Jetta after his foot “slipped” off the brake and onto the gas pedal, according to law enforcement sources.

Mosby was taken into custody after the Wednesday afternoon confrontation and waived his Miranda rights before allegedly telling cops the deadly encounter began when Velez Alvarez refused to let him merge in traffic.

He said the 2020 Chevrolet Silverado Velez Alvarez was driving veered into the driver-side mirror of his Jetta, scrapping the passenger side of the car, sources said.

Mosby then claimed Velez Alvarez blocked him in with the gray pickup truck on East 60th Street between Park and Third avenues — and then began berating him, according to the sources.

Mosby — who was driving with his girlfriend and three kids — claimed he feared for his and his family’s safety. He allegedly told cops he was trying to back out and get away when Velez Alvarez jumped out of the truck with “a large red knife,” and slashed his tires, sources said.

After popping the front and rear driver side tires, Mosby claimed Velez Alvarez walked in front of the Jetta — which is when, he said, his foot slipped on the pedals and the car lunged forward, according to the sources.

The older man was thrown across the sidewalk by the impact and slammed into a storefront, shattering the glass windows.

Mosby allegedly confirmed eyewitness accounts that he got out of his Jetta and yelled at the mortally injured man but told cops he did not remember what he said, according to the sources.

He said he then got back in his car, checked on his family and called 911.

Police arrested him and charged him with manslaughter and assault.

His Manhattan Criminal Court arraignment was pending Thursday.

Mosby’s girlfriend, Quenteria Daniels, 27, said he was driving her to work with their three young kids when the incident happened — and claimed Velez Alvarez had broken their car mirror and tried to block them in.

“He raised his hand with the knife at us,” Daniels told the New York Daily News.

“We were terrified. My kids were screaming and shouting.”

She told the News her and Mosby have been together for a decade and that, “I feel we are being let down because we were the original victims.”

“They are taking away a man from his children for trying to save them.”

Alvarez’s family, however, dismissed the self-defense claim on Thursday, telling The Post that the beloved and hard-working family man was not capable of such a violent outburst.

“My husband was so sweet, so kind,” grief-stricken widow Alex Garcia, 54, said. “He liked to care about other people. My husband is not going to hurt people. This does not make sense.”

“I can’t see this,” Garcia said. “When they tell me I say, ‘That’s not my husband. That’s not the man I’ve been married to for 28 years. Ask his friends, his family, his boss, his neighbors.

Alvarez, a native of Colombia, worked long hours as a construction supervisor to provide for her and their son, Steven, she said. 

The heartbroken woman said she couldn’t fathom her husband slashing someone’s tires.

“He eats oranges or apples in the car when he gets hungry,” she said from the family’s home in Franklin Square in Nassau County. “He peels the orange and cuts the apple with a small pocket knife. That’s the only knife I know.” 

“He is defending himself?” she said of Mosby. “No!”

New York State law allows residents to use deadly physical force to protect themselves — but only under a limited set of circumstances.

To get a manslaughter conviction, prosecutors would have to convince a jury that Mosby was reckless and knew his actions presented “an unjustifiable risk,” former Manhattan prosecutor Jeremy Saland said Thursday.

“This burden really falls on the prosecution to disprove the [self-defense] justification, but whether or not he’s legally justified is really going to call into question the evidence and the facts of that moment viewed by a reasonable person,” Saland said. 

“He tries to get away as a guy with a knife approaches his car, stabbing his tires,” he said. “It may not be justified but his justification was his intent to defend himself and protect his family and people in the car.”

But Julie Rendelman, a former Brooklyn assistant district attorney, said prosecutors could argue that Mosby went too far.

“The prosecution presumably would counter that the act of Alvarez slashing the tires of Mosby’s car did not rise to the level of deadly physical force, and therefore Mosby had no right to hit him with the vehicle,” she said. 

Mosby already has two prior arrests — a 2016 subway fare-beating rap and a Bronx robbery bust in 2017, sources and prosecutors said Thursday. 

In the robbery case, sources said Mosby and another man stole $400 from a person who was responding to an online ad to buy an iPhone. Instead of selling him the phone, the two crooks grabbed the cash and drove off. 

“He didn’t say anything,” the 25-year-old victim recalled to The Post Thursday. “He just took my money. He ran away.”

The Bronx man said that Mosby “was supposed to be locked up for a long time,” adding, “I don’t know why he’s outside.”

The Bronx District Attorney’s Office said Mosby was found guilty of fifth-degree criminal possession of stolen property in the case in December 2019 and was sentenced to a one-year conditional discharge and ordered to pay $400 restitution.

Additional reporting by Kevin Sheehan and Steven Vago