The United States has stopped observing two key provisions of the Vietnam cease-fire agreement, saying North Vietnam has failed to live up to all parts of the settlement.

In separate announcements yesterday, the Pentagon and the State Department said mine-clearing operations by the U.S. Navy in North Vietnamese waters had been halted and the chief American delegate to a joint U.S.-North Vietnamese economic commission had been called home from Paris.

By pulling Maurice Williams out of the Paris talks on an American economic aid program, the United States has halted its effort at carrying out Article 21 of the January 27 cease-fire agreement.

That provision pledges that "the United States will contribute to healing the wounds of war and to postwar reconstruction of the Democratic Republic of Vietnam."

By suspending the mine-sweeping operations, the United States is no longer complying with Article 2 of the Paris agreement, which states: "The United States will remove, permanently deactivate or destroy all the mines in the territorial waters, ports, harbors and waterways of North Vietnam as soon as this agreement goes into effect."

U.S. officials acknowledged yesterday that these are violations, but they charged that the North Vietnamese and their allies started the trouble by choosing those provisions of the settlement they would observe.

The American actions, or even the alleged continuous violations by Hanoi, do not indicate the peace agreement is in imminent jeopardy, U.S. officials said.

"The two actions today are similar to the bombing of Laos this week," one source said. "They are efforts to convince the Communists we mean business, not that we have given up on the agreement."