Greenwich Village activists are furious with a City Council member who campaigned last year to safeguard the neighborhood from overdevelopment because she approved a tech hub in Union Square without securing needed protections, they say.

Democratic Councilwoman Carlina Rivera last year vowed to support the $250 million, 21-story complex on 14th Street only if comprehensive zoning restrictions also got the OK.

But on Aug. 8, she voted yes to the 240,000-square-foot project without demanding height and other limits on commercial and residential development nearby, the activists say.

“This was an incredibly stinging disappointment,” said Andrew Berman of the Greenwich Village Society for Historic Preservation.

Rivera defended her vote, saying, “Voting no meant we would still get . . . the same threats of overdevelopment.”