President Carter promised families of the American hostages yesterday that he will order no military action that would endanger their lives, but officials immediately said his remarks signaled no change in deliberatley ambiguous U.S. threats to use military force to resolve the Iran crisis.

A senior State Department official said the president "in no way intended to rule out the use of force under all conditions" and earlier had told relatives of the hostages that he would not "look with passivity" if they are brought to trial as spies.

Carter's impromptu comments, which followed a private meeting at the State Department with the hostages' families, added a note of confusion to the administration's efforts to deal with the lastest statements from Iranian authorities.

Earlier in the day, responding to new Iranian threats to try some of the hostages as spies, White House and State Department officials pointedly reiterated an administration statement that included an implicit threat of U.S. military action.

That statement, issued Nov. 20 after Iran's revolutionary leader, Ayatollah Ruhollah Khomeini, first threatened to try the hostages as spies, said the United States was seeking a peaceful solution to the crisis -- "far preferable to the other remedies available." It added that the government of Iran "must recognize the gravity of the situation it has created."

The president and Secretary of State Cyrus R. Vance met for about 30 minutes yesterday with relatives of the hostages. One of those present, Judy Ehlenbeck of Overland City, Mo., said the families were promised government action soon to free the hostages. She refused to elaborate.

Leaving the State Department, Carter stopped in the lobby of the building, where he was cheered by department employes.

Declaring that "the one issue is the early and safe release of the American hostages from their captors in Tehran," the president said:

"I'm not going to take any military action that would cause bloodshed or arouse the unstable captors of our hostages to attack them or punish them. I'm going to be very moderate, very cautions."

Carter also used the occasion to criticize his main rival for the Democratic presidential nomination, Edward M. Kennedy (Mass.), for the senator's recent condemnation of the deposed shah, Mohammad Reza Pahlavi. Without mentioning Kennedy by name, the president said such statements will only delay the safe return of the hostages, who were captured Nov. 4.

"At this time, I am not interested in trying to resolve whether or not the shah was a good or a bad leader, or the history of Iran...," he said. "and we do not want to confuse the issue by interjecting these extraneous questions or debate into the present situation. If that does happen, it delays the date when we will see the American hostages come home."

A State Department official who was at Carter's meeting with the families said the president had stressed that he is not without means, short of military action, to influence Iran's decision on the question of spy trials. Some of these unspecified diplomatic measures are likely to be discussed with U.S. allies next week when Vance travels to Europe.

The president's visit to the State Department capped a day in which administration officials strove to grapple with the latest statements from Tehran and to dampen any signs of optimism at home.The focus was the statement early yesterday by Iranian Foreign Minister Sadegh Ghotbzadeh that some of the hostages will be freed, while not specifying which will be tried as spies.

In response, White House press secretary Jody Powell and State Department spokesman Hodding Carter reitarated the Nov. 20 warning of possible military action. If spy trials are held, Powell said, "the full responsibility for any ensuing consequences."

Powell also said that releasing some of the hostages will not soften the U.S. position which he said will prevail "if there is only one hostage left."

Almost from the outset, the administration has threatened military retaliation if any of the hostages were harmed. But it has deliberately not specified what other circumstances might prompt military action, as it has sought to head off the threatened spy trials and win release of the hostages.

In other developments yesterday:

A senior White House official asserted that Argentina this week rejected U.S. suggestions that it provide a permanent resident for the shah, citing among its reasons Kennedy's denunciation of the deposed ruler.The Argentine Embassy denied that Argentina had been negotiating to provide a haven for the shah.

Diplomatic sources in New York reported that United Nations Secretary General Kurt Waldheim has received no response from Iran on the unanimous Security Council resolution calling for the release of the hostages. The sources said the Security Council may meet Monday to receive a report from Waldheim.

More than 100 members of Congress, including leaders of both parties, urged immediate creation of a special military strike force to rescue U.S. embassies that fal under attack.

Meanwhile, the president's mother, Lillian Carter, who earlier said that if she had a million dollars she would hire some to kill Khomeini, said yesterday that she was not aware of what she was saying. She said she had been extremely tired and "they gave me a little bourbon and water [and] I didn't remember what I said."