Three Coast Guardsmen have been kicked off President Carter's honor guard because their superiors say their hair looks too short.

The three were not allowed to take their usual places in the honor guard which welcomed President Nicolae Ceausescu of Romania for fear "their whitewalls would stick out like a sore thumb," to quote the executive officer involved.

On Monday, the three Coast Guardsmen were hauled before their skipper at the Alexandria station. He fined each $200 and busted him one rank, from seamen to seamen apprentice, for violating the rules against extreme haircuts.

All but $50 of the fine and the demotion were suspended by Capt. W. W. Kohl, commander of the Alexandria Coast Guard station, where that service's honor guard is billeted.

The crackdown on short hair comes after years of military officers despairing of the long hair favored by their troops.

One of the punished seamen got a short "Marine haircut," and the other two got Mohawks, a cut that leaves a ridge of long hair running down the center of the otherwise closely cropped head.

"You could say it was a streak of craziness," Seaman David Spadoni, 20, of Nevada, Mo., told The Washington Post when quieried. "But we didn't expect to get the royal shaft for it."

Spadoni, insisting that the haircuts were a springtime lark rather than an attempt to embarrass the Coast Guard, said the visored caps worn by the honor guard would cover up the haircuts anyway, so he saw no need for the officers to get so upset. Spadoni is sporting the Marine haircut.

"We're trying to present a uniform appearance," countered Lt. Cdr. Robert H. Stracener, executive officer for the Coast Guard honor guard. "If I put three guys in that squad with those white sidewalls, I know I'm going to get a phone call. Their whitewalls would stick out like a sore thumb."

Stracener likened sending three Coast Guardsmen off to the White Coast Guardsmen off to the White House with extreme haircuts to letting a man go there with a black eye.

Spadoni said he and the two other seaman are appealing their punishment on grounds that it was too severe. He's also protesting to his home state congressional delegation.

In separate administrative actions, Stracener said Spadoni and Seaman Wesley Morris, 18, have been removed from the honor guard permanently, while Seaman Vincent Ferris will be kept off that duty until his hair grows out enough to hide the Mohawk streak.

Spadoni and Morris have been in minor trouble before the haircut episode, while Ferris has not, said a Coast Guard officer, in explaining the difference in penalties. All three will be evaluated over the next four months, Stracener added, to determine if they should be sent to petty officer school as the next step up in their Coast Guard careers.

"We weren't trying to embarrass the Coast Guard," said Spadoni of the haircuts. "If we had wanted to do that, all we would have had to do was to pass out on the White House lawn. We stand as tight a detail as anybody."

He contended other Coast Guardsmen have done worse things than get unusual haircuts, such as stealing or ripping a blouse off a woman, and gotten off easier.

Although most Coast Guardsmen volunteer for the honor guard duty of welcoming heads of state, serving at awards ceremonies and other official functions, Stracener said that the outfit is not composed entirely of volunteers. He stressed that serving in the honor guard demands maturity and a sense of responsibility and therefore makes special demands on the young Coast Guardsmen.

"They didn't think before they leaped," Stracener said.