Bloomberg told The New York Times the ban would limit the size of sweetened soft drinks that can be sold in delis, fast-food restaurants and sports arenas to 16 fluid ounces.
The measure, which will go before the New York City Board of Health in June, could take effect as soon as next March.
"Obesity is a nationwide problem, and all over the United States, public health officials are wringing their hands saying, 'Oh, this is terrible,' " Bloomberg said Wednesday in an interview. "New York City is not about wringing your hands; it's about doing something."
Diet sodas, fruit juices, dairy-based drinks and alcoholic beverages would be exempt. The ban also would not apply to beverages sold in grocery or convenience stores.
The New York City Beverage Association says soda is being unfairly singled out.
"The New York City health department's unhealthy obsession with attacking soft drinks is again pushing them over the top," spokesman Stefan Friedman said. "It's time for serious health professionals to move on and seek solutions that are going to actually curb obesity."