Const. Brian Montague says the VPD has taken the unusual step of sending warning letters to fewer than 10 demonstrators warning they could be charged criminally if they block the restaurant's owners or customers.
Police already have enough information to make at least one arrest, he said.
"The Vancouver police supports the fundamental freedom of peaceful assembly, but when public safety is at risk and civil disobedience turns to unlawful acts, the police have a duty to act on them," said Montague.
The protesters say they are fighting the gentrification of the neighbourhood.
But the operators of the restaurant say they are working with the community to improve life for those on the Downtown Eastside.
Over the weekend, one of the protesters was pepper-sprayed, but the victim refused to cooperate with the police investigation and nobody has been charged in the incident.