The U.N. is a place where there are always at least two sides to every issue. The fact that somebody is for something means that another group of nations is against it -- especially when that somebody is the United States.

But the current crises in Iran is a total exception to that rule. Whatever they may be ideologically, the diplomats here are all members of a club whose foundation has been shaken by the hostage-taking at the American Embassy in Tehran.

"The general feeling is that if this goes on, nobody's safe," said Gil Fernandes, the ambassador from Guinea-Bissau, the former Portugese colony that has taken a generally anti-American stance in U.N. affairs. "And so allof us have sympathy for the U.S. in this case -- perhaps for the first time," he added with a laugh.

The American, too, have felt this change of mood. It has carried over to an increased receptivity to U.S. views on other issues, they say.

"There is sympathy because they're professional diplomats and they know it can happen to them," said Richard Petree, a career man who is one of the American ambassadors here. "But there's also some sympathy because we are caught in this trap as a result of our superpower status."

An American legal expert, Robert Rosenstock, who has served here for over a decade, says that it is not strange that "everyone is horrified" by the holding of diplomatic hostages -- even those nations whose policy objectives include making trouble for the United States.

"What is interesting is that they are horrified pure and simple. There are no 'buts' about the shah, about oil, about 'interference' in Iranian affairs. Their opposition to the Iranian position is absolutely unqualified. No one is blaming us."

The Moslem countries are the ones most embarrassed by the Iranian actions.

The Libyans, for example, were among the first to initiate an approach to American officials here, express their concern, and offer any help they could give. (They could not give much because the Imam Musa Sadr, a leader of Lebanon's large Shiite community, disappeared while in Tripoli 14 months ago. This has not endeared the Libyans to Iran's current Shiite rulers.)

One Pakistani official went out of his way to explain to reporters that the Iranian stand constitutes a violation of the tenets of Islam, that the Prophet Mohammed himself showed punctilious respect for foreign emissaries.

Many diplomats, the Soviets in particular, have recoiled at the Iranian rationalization for the embassy take-over: the statement by Iran's acting foreign minister Abol Hassan Bani-Sadr that the embassy was not a true diplomatic post but "an espionage center" and "the actual center of the rule over Iran in the days of the ex-shah," according to a press release issued by the Iranian mission here.

"To accept this argument would be to threaten the sanctity of every Soviet diplomatic establishment in the world," said one Western ambassador. He admitted that it might threaten the sanctity of Western embassies as well. h

For most Third World countries their outrage was based on another reason. "We have only one thing in our hands -- the law," said an African ambassador. "Without the law, we have no protection. Iran should see its own interest in preserving this principle. So we hope that eventually this international pressure will be felt, because this is madness."

The only American action thus far that has given some Third World diplomats pause is the freezing of Iranian assets in the United Sates. Two diplomats -- one Arab and one African -- suggested that the unanimity of support for U.S. actions might begin to waver because of the threat that the freezing of assets posed for other nations with close economic ties to Washington.

But so far the unanimity remains. "We all have diplomats abroad. It is as simple as that," said Norwegian ambassador Ole Algard.