The United States is in the process of withdrawing from nearly all military cooperation with New Zealand because of its refusal to accept port calls from U.S. nuclear warships, administration officials said yesterday.

U.S. decisions to cancel or postpone a growing list of joint military exercises, conferences and exchanges of military personnel have been taken in recent days. Officials said this pattern will continue, probably for many months or even years, until New Zealand changes its nuclear policy.

Secretary of State George P. Shultz, sketching the rationale for the unusual if not unprecedented U.S. action, told the Senate Budget Committee on Tuesday that "New Zealand has basically taken a walk" from the ANZUS military alliance because of its refusal to accept port calls from U.S. nuclear-armed or nuclear-powered warships.

The ANZUS Treaty, signed in 1951, binds Australia, New Zealand and the United States in a defense relationship. Shultz said the treaty will be kept intact formally, at least on paper, so that "if there is a change of mind at some point down the road by New Zealand , it is there to be made operative again."

U.S. military cooperation with Australia will remain unaffected so far as possible, officials said. A statement issued yesterday in Shultz's name praised an Australian Cabinet statement supporting the ANZUS alliance and the continuation of U.S. ship visits.

New Zealand Prime Minister David Lange, whose antinuclear Labor Party was voted into power last July, is to be met in Los Angeles Tuesday by Deputy Assistant Secretary of State William A. Brown, the State Department announced. Lange, who will be en route to a conference in London, is to make a speech in California defending his government's nuclear views.

When he gets to London, according to reports in the British press, Lange will be told that his antinuclear policies will prevent British warships from visiting New Zealand ports. Britain, like the United States, refuses to say whether its warships are carrying nuclear weapons.

The relatively low level at which Lange is being met in California reflects an official view that not much progress is likely in discussions there.

"It probably will be a long time" before changes in New Zealand policy will permit restoration of the U.S. alliance relationship, a State Department official said. "It really is up to them."

Following New Zealand's refusal early this month to permit a visit by a U.S. warship, the United States announced its withdrawal from an ANZUS naval exercise and canceled an antisubmarine exercise with the New Zealand navy.

The Pentagon confirmed yesterday that three ANZUS conferences or meetings have been postponed indefinitely by the United States. The State Department said that a review of "overall cooperation" with New Zealand is not complete, but that the changes "reflect the need to readjust our military cooperation" in view of the ban on nuclear ships.

Pentagon officials said a case-by-case review of U.S. military cooperation with New Zealand had led to the deferral, cancellation or changing of most items studied, and that this is expected to continue.

New Zealand officers studying at U.S. service schools are being allowed to continue but in many cases will not be replaced when the school term is up, an official said.

Some U.S. arms sales are likely to continue to New Zealand as "a friendly government" but it will no longer be treated as an ally, the official added.