The crisis in Iran is approaching a new phase in which the United States expects other nations to begin showing increasingly "tangible" evidence of opposition to the takeover of the U.S. Embassy in Tehran, President Carter's national security affairs adviser, Zbigniew Brzezinski, said yesterday.

Interviewed on the television program "Face the Nation" (CBS, WDVM), Brezezinski strongly suggested that the United States is about to ask allies to begin taking financial and other economic measures against Iran in a renewed effort to win release of the 50 American hostages held there.

"I would expect that if this problem is not quickly resolved that the international community will proceed gradually to make its disapproval felt more tangibly," Brzezinski said.

Secretary of State Cyrus R. Vance left Washington last night on a tour of European captials, where he is to line up support of U.S. allies for collective action against Iran if the crisis continues.

Brzezinski declined to say what might trigger additional economic measures against Iran, but the immediate concern of U.S. officials is the threat by Iranian authorities to try some of the hostages as spies.

Iranian Foreign Minister Sadegh Ghotbzadeh reiterated yesterday his country's intention to form an international tribunal to investigate "American wrongdoings" in Iran, including alleged spying by U.S. Embassy personnel since last year's revolution toppled the deposed Shah Mohammad Reza Pahlavi.

Asked about likely U.S. reaction to spy trials, Brzezinski said "any further abuse, of these already maltreated hostages would give us very grave concern and we could hardly afford to sit by as spectators.

"What precisely we might do is hard to foretell," he continued. "But even without trials, Iran's continued defiance of the international community will call for further indications to Iran that this kind of posture is self-defeating, destructive and costly."

Administration officaials have made it clear the last several days that the time is rapidly approaching for more concerted, collective action against Iran. On Friday, the president told families of the American hostages that if Iran goes forward with spy trials the United States "would take steps to interrupt commerce with Iran."

The United States already has acted unilaterally by cutting off imports of oil from Iran and by freezing Iranian government assets in the United States. The administration has also, until now, been satisfied with the response of U.S. allies, which Brzezinski characterized yesterday as "strong condemnation" of Iran during the now concluding "first phase" of the crisis.

During his European tour, Vance is expected to ask U.S. allies, including Japanese officials with whom he will meet in Paris, to increase gradually economic pressure on Iran. This could begin with such measures as freezing Iranian assets of suspending bank transactions, which would greatly complicate Iran's ability to engage in international commerce.

Beyond that, the allies could suspend commitments to provide financial and others assistance to Iran for planned capital improvement projects such as construction of oil refining facilities.

The most drastic step, and the one U.S. allies would be most reluctant to take, would be to cut off Iraian oil imports. Japan and the nations of Western Europe are far more dependent on foreign oil imports, from Iran and elsewhere in the Middle East, than is the United States.

A series of such measures by U.S. allies would not only increase pressure on Iran, but might serve to calm public outrage in the United States over the prolonged crisis, which began Nov. 4 with the takeover of the embassy.

There is fear among administration officals that lengthy "show trials" of the hostages, filled with anti-American propaganda which would be broadcast worldwide, would inflame American public opinion and place the administration under intense pressure to end the crisis with one decisive act.

But there is also uncertainty in the administration over the purpose of the international tribunal Iranian authorities propose to convene. The most optimistic assessment is that this may be the beginning of a way out of the crisis for Iran, to be used for quick trials of some of the hostages as spies, followed by their expulsion.

The United States might find this tolerable, but would almost certianly take additional steps if the tribunal becomes, in Brzezinski's words, "a hostile propaganda spectacular directed at the United States."

Brzezinski stressed the importance of maintaining "international solidarity" in dealing with Iran. In a suggestion of possible U.S. military action if U.S. allies do not cooperate with the efforts, he said that if such solidarity is lost "we might be forced to rely on other remedies."