NEW YORK » You’d better watch out. You’d better not fight. Better not be a lout. And SantaCon’s telling you why.

The annual holiday flash-mob-meets-pub-crawl is reining itself in for Saturday’s New York City festivities, which fall on the same day as a planned protest over killings by police.

SantaCon organizers have retained a noted civil-rights lawyer to advise on the do’s and don’ts of public gatherings, and leaders met with police Friday. Expressing respect for the demonstration, they’re instructing participants to stick to bars that welcome them and party inside instead of on the streets.

"It’s more important this year than ever to pace yourself, watch out for your elves and stay safe," their website warns, adding that bad behavior may mean the ultimate lump of coal: no SantaCon next year.

It’s a sobering message for SantaCon, which has faced mounting pressure from politicians, police and community groups as it has grown from hundreds to thousands of costumed participants in roughly a decade.

The event was set to start at 9 a.m. for a press conference in Times Square before participants hit bars in the Hell’s Kitchen area and nearby mid-Manhattan.

"Hopefully, tomorrow will be a very positive event, and then we can build on that to have a transition" to a better-received SantaCon, said lawyer Norman Siegel, a former New York Civil Liberties Union leader. He said if all goes well, participants plan to apply next year for a permit to walk in the street, rather than on sidewalks they’ve been lambasted for crowding.

Aficionados say SantaCon is lighthearted communal fun that tweaks the nose of Christmastime consumerism. Participants are urged to bring gifts to hand out or prepare performances, and organizers stress that last year’s event raised about $60,000 for charities.

"It was truly a spectacle of epic proportions" when Liz McManus went for the first time in 2010 at age 22, enjoying a day of singing, laughter and making new acquaintances. She went twice more but has been put off by reports of misbehavior since.

Some residents see SantaCon as an onslaught of crass Kringles, soused elves and anything-but-grandmotherly Mrs. Clauses. There have been two arrests and 85 summonses for disorderly conduct, open alcohol containers and other offenses during the last two SantaCons, and an online video captured people in Santa suits fighting on the evening of last year’s SantaCon.

"Pro: The event raises money for kids that need therapy," host Jimmy Fallon said on NBC’s "The Tonight Show" this week. "Con: Specifically, the ones that need therapy after seeing Santa take a leak behind a dumpster."

Bar owners are split, with some welcoming the daytime business and others saying SantaCon is too rowdy.

Anti-Con sentiment started peaking last year, as residents of Manhattan’s bar-filled Lower East Side posted "SantaCon free zone" signs, local commuter railroads began banning alcoholic drinks on their trains during the gathering, and a police lieutenant suggested to midtown Manhattan bars that the event hurt the neighborhood, though the then-police commissioner expressed support for it.

With prodding from city and state officeholders, organizers let police and community leaders know their planned route and tasked volunteers with helping keep participants in line.

But "all those efforts really don’t make up for the fact that this is a group of people who largely come to drink," state Sen. Brad Hoylman said Friday. "It amounts to an epic pub crawl that is very difficult to control."

Thoughts of bringing the event to Brooklyn’s Bushwick neighborhood this year were scuttled as a city councilman urged bars not to participate and the Parks Department said no to using a local park as a meet-up point.

And Hoylman, state Assemblyman Richard Gottfried and City Councilman Corey Johnson sent organizers a letter Friday urging them not to return to Hell’s Kitchen in future.

But for now, SantaCon is coming to town with a nice-not-naughty message.

"NYC Santa realizes that he has a responsibility to New York City and its citizens," the organizers say on their website. "Santa Loves NYC."