George Bush the former CIA director seeking the Republican presidential nomination, said today "it is not intervention" in another country's affairs for the United States to support friendly governments facing revolution, like the shah of Iran.

"That's not meddling," he said, "that's supporting."

Taking a hard line on foreign policy. Bush criticized President Carter's approach to the Iranian crisis as "backing and filing." He said the president's human rights policy speeded up change in Iran and added that once the president alerted troops for a possible show of force in Iran, he should have followed through to make "it clear we wouldn't let others mingle in the affairs of other nations."

Bush's remarks came during a sometimes testy news conference on the second day of his official candidacy. At one point a reporter shouted at him. "Aren't you vicillating?" as Bush fielded questions on how he would have handled Iran.

Finally, Bush said he did not have enough information to know whether he would have alerted troops for a possible show of force in Iran But said once Carter had done so, he should not have pulled back.

Also at his morning news conference here in the capital of the state with the nation's first presidential primary election of 1980, Bush announced that former governor Hugh Gregg would manage his New Hampshire campaign.

In 1976 Gregg managed Ronald Reagan's campaign here, an effort that came close to defeating an incumbent president in the Republican primary.

But Bush's remarks on Iran dominated his news conference, a result of statements he made Tuesday in Hartford in the midst of a seven-state tour following his formal announcement for the presidency Tuesday. There, he said he believed the United States "might have shaped events" in Iran.

On the topic of covert actions he cited "destabilizing" of Hitler's Third Reich as a case where covert activities might have been warranted.

In his campaign Bush emphasizes he experience in foreign affairs - at the CIA, as ambassador to the United Nations, as envoy to China - as part of his qualifications for the presidency. Thus his views on intervention and international affairs could prove important in his campaign.

Bush said he "would have made clear . . . we would give full support to the shah." He added that it was "in the interests of the free world to support the shah."

Bush did not spell out what full support of the shah would have been, but said it included "making it clear we wouldn't let others mingle in the affairs of other nations." At a later stop in Burlington, Vt., he said U.S. troops in Iran would not have been warranted.

On U.S. assistance, he said, "I don't see that as intervention in their internal affairs.

"It is not intervention when you support a friendly government. I don't see that as intervention in their internal affairs.

Bush was scheduled to leave New England tonight for Florida and further campaigning there and in Alabama. CAPTION: Picture, George Bush has members of his family lined up behind him as he announces his candidacy. He made the declaration Tuesday at the National Press Club. UPI