President Carter said yesterday that his "inclination is to prosecute former attorney general Ramsey Clark and nine other Americans who went to Iran in definance of the president's ban on travel to that country by U.S. citizens.

In an impromptu news conference aboard Air Force One, Carter also said he is reconsidering his refusal to debate independent presidential candidate John B. Anderson and might agree to a formula that would open the debate to candidates on the ballot in enough states to have "at least a theoretical possibility of winning."

The president, who was returning here after a trip to Miami, Seattle and Grand Island, Neb., went to special lengths to underscore his concern and annoyance about Clark's participation last week in a Tehran conference probing alleged crimes committed by the United States in Iran.

"My inclination is, within the bounds of the law, to go ahead and prosecute both Clark and the others who went against my directive, which was legal," Carter said.

In expressing that view, he appeared to be running counter to the attitudes of his new secretary of state, Edmund S. Muskie. During a Sunday television interview, Muskie said the main purpose of the ban on travel to Iran was to dissuade Americans from going to places where they might be in danger, and he implied strongly that it would be unwise to prosecute Clark and the others.

However, Carter brushed aside reminders of Muskie's remarks by saying: "I don't think Ed Muskie has any legal responsibility for determining who to prosecute or not to prosecute.

"I do have some legal responsibility, working primarily through the attorney general, and my own inclination is to enforce the directive, which I presume to be legal, and when people violate it, to see that an appropriate punishment is levied."

Carter said Attorney General Benjamin R. Civiletti, who has been assigned primary responsibility for handling the Clark case, "will make a decision on whether that should be to seek civil penalties or criminal penalties."

"I would guess civil penalties would be more appropriate," Carter said. While adding that "I am not trying to discount the possibility of criminal prosecution," Carter noted:

"I think the most likely move would be civil in nature because we need to let the American people know, and the rest of the world know, that the order will be enforced to deter further violation of it in the future."

The president's remarks appeared to align him with those conservative members of Congress, mostly Republicans, who have criticized Clark harshly and demanded punishment.

However, Carter's attitude is at variance not only with the position implied by Muskie but also with those of a number of other officials in his administration. They are known to believe that prosecuting Clark could enmesh the government in a tangle of diplomatic and legal problems.

Some fear that prosecution would give additional publicity to the anti-American charges made at the Tehran conference and might be used by Iranian militants as a pretext for further delays in releasing the 53 American hostages.

Others, noting that legal opinions are sharply divided about whether the president can bar U.S. citizens from travel abroad, are concerned that prosecution would lead to extended litigation and appeals that would make even more difficult and confusing the government's ability to regulate overseas travel by Americans.

However, Carter, who said several times that he believes his travel ban is "legally valid," left the impression that his annoyance at Clark's action outweighs these considerations. Calling Clark and the others "misguided Americans," the president said:

"Well, the irony is apparent in a former attorney general attending a conference designed to prove the criminality of his own country. I think that's much more ironic than the fact that an attorney general is being accused of violating the law."

After being informed of the president's comments, Clark, who has stayed in Paris since leaving Iran, told CBS News: "Well, I'm saddened by it, a little bit. I love our country, and I believe in the presidency, but I don't think President Carter understands what law is. . . .

"More important, I don't think he understands freedom. He believes in absolute obedience to authority. When the president says 'thou shalt not,' every single American is supposed to stand at attention."

In an interview with Associated Press, Clark said that giving the Iranian parliament the power to decide the hostages' fate "sounds like good government to me." He said that the hostages will remain captive as long as the Iranians perceive the United States as "an angry face, threatening them, seeking to bully them."

[Clark also called the aborted U.S. effort in late April to free the Americans an act of aggression.]

Referring to the controversy over his decision not to debate Rep. Anderson (R-Ill.), Carter said he didn't want third-party candidates to interfere with a "head-to-head" debate between himself and Ronald Reagan, the likely Republican presidential nominee.

But, while stressing that he still opposes "a three-person debate," Carter said, "I wouldn't foreclose the possibility of other debates as well."

He said it would be necessary to find a formula for determining which other opponents he might debate and suggested it might involve such factors as whether the candidate is on the ballot in enough states to theoretically win a majority in the electoral college.

Asked if that meant he has changed his mind about debating Anderson, the president said only that "to some degree, it is a change."

Anderson, campaigning in San Francisco, said he was "very, very pleased" by Carter's remarks and added that he would "gladly accept" and chance to debate the president directly. Noting polls showing that many people objected to Carter's original decision not to debate him, Anderson said that Carter "is beginning to feel the hot breath of public opinion."

Talking about foreign policy, Carter said he still hopes to win Senate approval of the strategic arms limitation treaty (SALT II), which was shelved in the wake of the Soviet invasion of Afghanistan, and added that the administration is 'exploring" the possibilities of negotiating a SALT III agreement with the Soviet Union.

Although he did not elaborate, reliable sources said that at a foreign affairs breakfast of top administration officials last Friday, and at a followup meeting, it was made clear that the president wants to mount a new Senate effort on SALT II as soon as possible.

The sources stressed though that it is unlikely that anything will be done until after the November elections.

As to SALT III, the sources said considerable analysis and consultation is going on between Wednesday and its European allies about how to engage the Soviets in talks involving European-based, intermediate-range missiles.

That would be one of the major topics of a SALT III negotiation, although the Soviets have said they will not discuss the subject unless the Western allies drop a program for modernizing their European defenses with missiles capable of reaching Soviet soil.