Robertson called the discovery of a 69-year-old man's body in a tent at the park tragic and said it was time the tents came down.
Police have said the death, at this time, does not appear to be suspicious but an autopsy will be held to determine its cause.
Robertson says the city is not looking for confrontation.
"I hope we see the tents coming down during the day and into the evening and people continuing to move into shelter spaces," he told an afternoon news conference."
The mayor says the city has moved more than 100 people into shelter from Oppenheimer Park, more than half of them into actual housing and there are still more than 100 shelter beds available.
He said city staff are meeting with people to ensure they understand the available shelter options and to help them take down the structures and that police would be simply "standing by" to assist should they be required.
"The focus is to help people take the tents down by city staff and engineers and park, police are just there," said Robertson.
"The city has recognized with all these tent camps in the past that it does take time. It’s not a hard-fast stop.That’s never been the case with tent camps as the time expires."
The mayor says the police will have greater enforcement powers after 10 p.m. PT thanks to a B.C. Supreme Court order that will put campers in tents in contempt of court.
But he said police are only there in case of an emergency or to support city staff "should things go sideways."