A high school basketball tournament on the Northern California coast has become the latest flashpoint in nationwide protests over police killings of unarmed black men.

The boys and girls varsity basketball teams from Mendocino High School were disinvited from a tournament that starts on Monday at nearby Fort Bragg High, because of concerns players would wear T-shirts with the words “I Can’t Breathe” printed on them while warming up.

Several professional basketball players have worn “I Can’t Breathe” shirts during pre-game warmups, as have stars of the NFL. The slogan refers to the final words of Eric Garner, a New York man who died after being placed in an illegal chokehold during an arrest by NYPD officers in July. A grand jury decision not to indict the officer involved led to widespread protests in New York last month.

The deaths of other black men at the hands of police – most notably that of Michael Brown, an unarmed 18-year-old, in Ferguson, Missouri in August – have also contributed to protests across the US.

Mendocino unified school district superintendent Jason Morse said the boys team was reinstated after all but one player agreed not to wear the shirts anywhere on the Fort Bragg campus during the three-day tournament, but too few girls accepted the condition for the team to field a tournament squad.

Brian Triplett, the athletic director at Fort Bragg High, did not return a call and email seeking comment. Principal Rebecca Walker issued a written statement on Friday saying school administrators respected the Mendocino teams “for paying attention to what is going on in the world around them” and that the T-shirts were being prohibited as a security precaution.

“To protect the safety and well-being of all tournament participants it is necessary to ensure that all political statements and or protests are kept away from this tournament,” wrote Walker, who said she was speaking on behalf of the athletic director and the Fort Bragg school superintendent. “We are a small school district that simply does not have the resources to ensure the safety and well-being of our staff, students and guests at the tournament should someone get upset and choose to act out.”

Mendocino varsity teams first wore the “I Can’t Breathe” t-shirts before a game with Fort Bragg on 16 December, according to the girls coach, Caedyn Feehan. The girls also wore them before games at two other tournaments and didn’t receive any blowback, Feehan said.

“I didn’t even know what it meant. I thought it was a joke about how I had conditioned them so hard,” Feehan said. “None of the administrators knew what it was or that any of them were doing it in advance. This was entirely for their cause that they had strong feelings about.”

Professional basketball players such as LeBron James, Derrick Rose and Kyrie Irving wore “I Can’t Breathe” shirts during warm-ups this month without repercussions from the NBA. After Kobe Bryant and other Lakers players wore them before a game and on the bench on 9 December, coach Byron Scott said he viewed it as a matter of “freedom of choice and freedom of speech”.

That’s how Marc Woods, whose 16-year-old son Connor plans to sit out the tournament, sees it. Connor wore the t-shirt at the 16 December game in the name of team solidarity, but “now that’s become a first amendment violation, that’s what he is fired up about”, the father said.

Woods said he was outraged by what he sees as using intimidation to silence players and fans. Fort Bragg administrators have warned spectators who plan to protest the t-shirt ban that they will be asked to leave, he said.

“It doesn’t take a lot to suppress the exchange of ideas when you put fear into it,” Woods said.

Both schools are in Mendocino County, known for redwood forests, rugged coastline and marijuana-growing, located 120 miles north of San Francisco. The student bodies at the two schools are 1% black and 50% white and 41% Hispanic at Fort Bragg, 75% white and 9% Hispanic at Mendocino.

A county sheriff’s deputy, Ricky Del Fiorentino, was killed in March by a man suspected of murder and carjacking in Eugene, Oregon. The suspect was killed by a Fort Bragg police officer.

Walker referenced Del Fiorentino’s death, saying: “We simply feel this issue is too emotionally charged to allow such a demonstration to happen in our tournament and be able to ensure the safety and well-being of all involved.”