The United States yesterday accused North Korea of an "act of lawlessness" in firing a surface-to-air missile at an American spy plane flying at high altitude off the west coast of the Korean peninsula.

The two-man SR71 plane was in South Korean and international air space during its flight, State Department spokesman Dean Fischer said. He announced that the United States had confirmed the missile firing and demanded a meeting of the Military Armistice Command to make a direct protest about the incident. The command oversees the truce between North Korea and South Korea.

"The United States government expresses its serious concern at this act of lawlessness, which constitutes a violation of international law, the Korean armistice agreement and accepted norms of international behavior," Fischer said.

He called the SR71 mission "one of a number of routine flights which have been conducted over a period of years in the area." The plane, which can fly faster than 2,000 mph and reach altitudes above 80,000 feet, was not hit by the missile, which exploded a few miles away, Pentagon spokesman Henry Catto said. He said the SR71 crew "reported spotting a contrail and subsequent airburst several miles distant."

Catto said the United States did not provoke the North Koreans in any way. Other U.S. officials said the SR71 did not stray accidentally or deliberately from its course through airspace the United States considers to be South Korean or international.

It was the second military incident in a week involving U.S. aircraft over a disputed border area. Two Navy Fl4s shot down two Soviet-made Libyan jets over the Gulf of Sidra last week.

in Oakland, Calif., yesterday, White House counselor Edwin Meese III said U.S. planes may be ordered to fire back if an attack similar to that on the SR71 occurs again, Associated Press reported.

meese declined to say precisely what steps might be taken. "One hypothetical option would be to take out the source of the missile," or launch a counterattack, he said, after confirmation that the attack was intentional.

[in Santa Barbara, Calif., White House deputy press secretary Larry Speakes, asked about Meese's comments, aid: "He's reflecting the president's policy," AP said.]

North Korea frequently has protested flights over the coastal area where the missile reportedly was fired Wednesday. The United States considers the area South Korean or international airspace, but North Korea disputes control of some of the region.

On occasion, North Korean gunboats have seized South Korea fishing boats in the area. Two weeks ago, two North Korean Mig21s flew over one of the five islands in the area controlled by South Korea but claimed by North Korea.

However, while it is not new that Pyongyang does not like them, sources here said, spy flights have been conducted on a regular basis for years, and are not a result of a decision to assert U.S. rights, as was last week's Navy exercise in the Mediterrnean area. Washington considers the Gulf of Sidra international waters, but Libya claims it as part of its territorial waters.

Fischer said the United States is contacting China and the Soviet Union "to request that they convey our deep concern over this incident to North Korean authorities and that North Korea avoid any repetition of such dangerous activity."

"We believe it imperative to use these channels to impress upon the North Koreans the seriousness with which we view this incident," Fischer said. The United States and North Korea do not have diplomatic relations.

North Korea issued no statement on the incident, and there was no North Korean confirmation that a missile had been fired. North Korea also had not responded to the U.S. call for a meeting Saturday of the armistice commission.

[yesterday, however, North Korea charged the United States with "provocations" dating back 10 days along the demilitarized zone dividing the Korean peninsula, United Press International reported. A dispatch of the North Korean Central News Agency monitored in Tokyo accused U.S. troops of more than 60 provocative acts.]

The United States, as in the Libyan incident, gave a high priority to stressing that it would not be intimidated.

"We intend to continue to fly these routine flights and will take whatever steps are necessary to assure the future safety of our pilots and planes," Fischer said. He declined to comment on whether the United States would take military action to protect SR71 flights or to retaliate for the firing of the SA2 missile.

President Reagan, vacationing at his California ranch, was told about the missile firing Wednesday morning about 8 1/2 hours after it occurred. Meese said Reagan "was concerned about it, obviously." At that time, however, the firing of the missile had not been confirmed, and the president had no comment.

Since the Korean War ended in 1953, the demilitarized zone separating the two Koreas has been the scene of a series of armed clashes. No surface-to-air missile has been reported fired at a U.S. plane before, but two American aircraft have been shot down by North Korea.

On April 15, 1969, gunners shot down a propeller-driven Navy EC121 spy plane over the Sea of Japan about 100 miles off the Korean coast. All 31 U.S. crewmen were killed. North Korea claimed that the plane had intruded into North Korean airspace, but the United States said it was at least 50 nautical miles offshore.

On July 13, 1977, an Army helicopter mistakenly crossed the demilitarized zone and was shot down, killing three Americans and wounding one. There are 30,400 U.S. Army personnel in South Korea. President Carter announced plans in 1977 for a phased withdrawal of all U.S. ground forces there within four or five years. Two years later, he halted withdrawals.