The mayor wants to shut down six miles of road along the Embarcadero between the Bayview and Chinatown during two days this summer, between 9 a.m. and 1 p.m.
The idea is to encourage more walkers, joggers and bikers along the route.
But the plan has some critics.
"I recognize some businesses, not all; in fact I would argue the majority of businesses along the route are favorable to this because they recognize the opportunity to connect people to their businesses in ways they may not feel connected when they're driving by at 45 mph," Mayor Newsom said.
The so-called Sunday Streets days are planned for August 31 and September 14.