The directive comes after more than 100 nights of demonstrations that have seen police officers and federal agents use the chemical agent, which is a powerful type of tear gas, to disperse protesters.
“During the last hundred days Portland, Multnomah County and state police have all relied on CS gas where there is a threat to life safety,” Wheeler, who is also the police commissioner, said in a video Thursday. “We need something different. We need it now.”
The city has been sued over the use of CS gas and some elected leaders have called for authorities to stop using it. A couple sued the city after they claimed to be exposed to tear gas during the downtown protests, the Oregonian reported.
In July, inmates in the Multnomah County Justice Center complained of gas seeping into their cells, prompting some to hit their panic buttons and put their mouths at the base of the cell doors in an effort to breathe.
The American Civil Liberties Union, which has sued over the actions of federal agents in Portland, tweeted the agent is banned in warfare.
"It has become the first resort weapon to disperse and suppress peaceful protesters with little regulation, accountability and oversight," Jamil Dakwar, director of the ACLU Human Rights Program, said in a video.
Many of the demonstrations against police brutality have seen a range of crimes committed, including arson, assault and fatal shootings.
"Arson, vandalism and violence are not going to drive change in this community," Wheeler said. "I expect the police to arrest people who engage in criminal acts. And I expect the rest of the criminal justice system to hold those individuals accountable."
On Wednesday, Wheeler's office told the newspaper that three police officers were reassigned to desk duty pending investigations into their conduct during the demonstrations. One officer was seen on video slamming a protester to the ground and hitting the individual repeatedly in the head.