The New York Police Department plans to step up enforcement of bicycle safety in parts of the city that have seen a disproportionately higher rate of collisions involving bicyclists, city officials said Thursday.

The initiative, which would be aimed at common cycling infractions like running red lights or riding on the sidewalk, comes after numerous complaints about two-wheeled scofflaws and recent protests against new bicycle lanes added to streets in Brooklyn and downtown Manhattan.

“We’ve installed 250 miles of lane over the last four years and thousands of new bike racks,” Janette Sadik-Khan, the city’s transportation commissioner, said at a news conference. “We have been friendly to cyclists. Now it’s time for cyclists to be friendlier to the city.”

Ms. Sadik-Khan, a cyclist herself, has led the Bloomberg administration’s efforts to siphon off city road space from automobiles in favor of pedestrians and bicyclists, an effort that officials say creates a more balanced use of the city’s streets. Critics charge that City Hall has placed a stigma on car ownership and unilaterally removed traffic lanes for the use of a small minority of residents.