SACRAMENTO — Gov. Gavin Newsom recommended late Wednesday that Californians postpone or cancel all large gatherings until at least the end of March to slow the spread of the novel coronavirus.

Under a new policy issued by his Department of Public Health, Newsom said public events should be limited to no more than 250 people and should not proceed unless organizers could ensure at least 6 feet of distance between attendees. Gatherings of people who are at high risk of contracting the virus, he said, should be kept to 10 or less.

“Changing our actions for a short period of time will save the life of one or more people you know,” Newsom said in a statement. “That’s the choice before us. Each of us has extraordinary power to slow the spread of this disease.”

Because it is merely a guidance, the policy does not carry the force of law. But state public health experts urged Californians to cancel concerts, conferences and sporting events, as well as smaller events in crowded venues such as auditoriums.

The state recommended that policies not meeting that criteria should only continue if they are considered essential and cannot be postponed or carried out by another means.

“The people in our lives who are most at risk —seniors and those with underlying health conditions — are depending on all of us to make the right choice,” Newsom said.

By Wednesday, California had 190 confirmed cases of coronavirus, including 108 in the Bay Area.

Earlier in the day, San Francisco banned all gatherings larger than 1,000 people. President Trump limited travel to the United States from Europe for 30 days and the NBA suspended its season after a player tested positive for the virus. Actor Tom Hanks announced that he and wife Rita Wilson had both tested positive for the coronavirus, the highest-profile case yet of the illness.

Alexei Koseff is a San Francisco Chronicle staff writer. Email: alexei.koseff@sfchronicle.com Twitter: @akoseff