The mayor said the protesters need to "chill out" and follow the process laid out by the city.
"We are re-evaluating our entire relationship and how we engage with Occupy Philadelphia," Nutter told reporters.
Earlier in the night, Gwen Snyder, an Occupy participant, said the protesters thought they were obeying the city's eviction notice by moving across the street.
At 11 p.m., after being told to move back to Dilworth Plaza, some protesters tried to storm an entrance into City Hall, demanding to speak with Mayor Nutter. They were met by cops in riot gear, but no arrests were reported.
The scene had calmed down an hour later, as Nutter was preparing to address the Occupiers.
Yesterday's vote to move followed a meeting that began indoors, at the Friends Center at 15th and Cherry streets, and ended outdoors, on the west side of City Hall.
It was a heavily debated decision that came hours after 24 protesters - at least half of whom were Occupy Philly members - were arrested during a sit-in at the Market Street Bridge.
The sit-in followed a march of a few hundred demonstrators, including Occupy members, unemployed workers, activists and other supporters, from City Hall to the bridge, in what may have been the biggest push by the "99 percent" in Philadelphia since the local movement started last month.
After last night's general-assembly meeting, several Occupiers began relocating parts of the tent city that had grown on the plaza over the past six weeks.
"I think it's a great move forward for the movement," said Dave Marley, 34, a musician from South Jersey.
He said he didn't participate in the vote because he hasn't been sleeping at the Occupy site.
But members weren't sure that all Occupiers would heed the majority opinion and move overnight.
