Teen heartthrob Justin Bieber got a scare Thursday when an undercover cop was mistaken for a crazed fan at a Midtown promotional event and was grabbed by one of the singer’s bodyguards. Hit the jump to read the rest of the story.

@WiL

Teen heartthrob Justin Bieber got a scare Thursday when an undercover cop was mistaken for a crazed fan at a Midtown promotional event and was grabbed by one of the singer’s bodyguards, police said.

The incident outside Macy’s flagship store in Herald Square happened as a large crowd of mostly screaming teenage girls surged toward the 17-year-old “Baby” singer, knocking down metal police barricades.

When an unidentified plainclothes cop stepped up to protect Bieber from the unruly crowd, one of the Canadian crooner’s bodyguards grabbed him and tried to pull him away.

Bieber was quickly ushered into the store, where he signed autographs and launched his new fragrance, “Someday.”

Once the dust settled, the overprotective bodyguard was issued a summons for disorderly conduct, police said.

“He \[Bieber\] was walking into the store and people got too excited and started pushing the barrier down,” said Tara Robinson, 18, who spent three hours waiting in the intermittent rain to get a glimpse of the pop sensation.

“He didn’t even have time to wave at his fans,” Tara said. “I was yelling ‘Justin!’ They ruined the moment for us.”

Cops denied initial media reports that a man jumped the barricades and attacked Bieber, knocking him to the ground.

“Bieber wasn’t touched. Bieber wasn’t hurt,” a police source said.

Bieber was not scheduled to venture outside the store to greet fans, but decided at the last minute to appease the crowd chanting “We want Bieber!” and singing his hit song “Baby.”

Some fans had been camped out since 5 a.m.

Amber Wende, 13, of south Jersey, and three of her friends had one of their mothers drive them to the city before dawn so they could track Bieber’s every move.

“We went to the ‘Today’ show, then ‘The View’ and to Macy’s,” said Amber, huddled with her pals under a purple blanket plastered with Bieber’s face.

Amber said they nearly fainted when they saw Bieber getting into a car outside the “Today” show.

DN