A Brooklyn woman was beaten by a trio of would-be robbers after a seemingly pleasant interaction went south, authorities said.

The 30-year-old was walking on West 25th Street in Chelsea toward the 23rd Street C train station around 8 p.m. Monday when she passed the strangers sitting on a stoop and said, “Hi,” police said Wednesday.

“Suck my d–k,” one of the brutes responded, the victim told police.

As the woman crossed the street to enter the train station, the trio approached her from behind and kicked her in the back — sending her tumbling down the stairs, police said.

When she tried swiping herself into the station, they began attacking her — punching her in the face as one of the men repeatedly demanded money, cops said.

The group was scared off when a straphanger entered the subway station.

The woman suffered bruises to her hairline and face, but refused medical attention at the scene, police said.

Police released footage of her attackers, whom they describe as approximately 15 to 18 years old.