The new standards, hailed by advocates as the toughest action by any city on climate change so far, takes aim at the biggest source of greenhouse gases in NY, where buildings account for more than two-thirds of emissions. "This is the city that has suffered because of global warming and we are still vulnerable", said de Blasio, referencing the devastation caused by Superstorm Sandy in 2012.
Buildings that fail to meet the marks will be punished by major fines. "Cut your emissions or we'll cut something you really care about: We'll take your money".
De Blasio had originally planned to hold the rally outside the 5th Avenue building but inclement weather forced the group to move inside the building that houses President Donald Trump's Manhattan home, the New York Post reported.
De Blasio, a Democrat who won a second term as mayor in 2017, has been openly mulling a presidential bid.
Trying to make light of the rather farcical scene, de Blasio joked about the pro-Trumpers trying to "serenade us".
According to city officials, the president's eight largest NY properties pump out around 27,000 tons of planet-warming gases every year, the equivalent of 5,800 cars. "If you don't do it by 2030 there will be serious fines, as high as $1 million or more for the biggest buildings".
Raw video: Mayor Bill de Blasio holds event inside Trump Tower to announce his Green New Deal saying the city will move to 100 percent renewable energy.
NY has positioned itself as a bulwark against Trump administration attempts to dismantle action to address climate change. "If people want to offer their opposition, it doesn't change me one bit", he said. The law, which takes effect May 17, compels owners of residential and commercial buildings larger than 25,000 square feet (2,300 square meters), to install new boilers, air conditioners, windows and insulation in order to meet sharp carbon-emission reductions.
"We will do what's necessary to combat the climate crisis".
Responding to a reporter's question, De Blasio - still straining to be heard - said he was discussing a possible presidential run with his family.
Keeping to NYC, De Blasio's $14 billion deal would cut down greenhouse gas emissions by 30 percent by 2030.