Chinese Vice Premier Teng Hsiao-ping today criticized the Carter administration's policy toward Iran, saying that the United States showed a lack of direction on the crisis there and mishandled it.

He rebuked the Carter administration for failing to take a tougher line against Soviet interference in Iran, Africa and elsewhere. According to reports of his talks with Japanese officials, Teng said the United States "is allowing the Soviet Union to place a lot of pawns on the world's chessboard" and that "things cannot be allowed to go on this way."

Teng told former Japanese premier Takeo Fukuda that the United States has shown indecision and that Washington's "handling of the [Iran] crisis lacks direction," according to a top Fukuda aide.

On a brief visit here en route home from his American tour, the Chinese leader said that as a guest in the United States he was not able to express any criticism.

Teng bluntly contradicted Fukuda when the former Japanese premier said he was not aware of any Soviet interference in Iran.

Teng said that the Soviet Union already had interfered in Iran and that this raised the possibility of a "domino reaction" that might spread to countries like Saudi Arabia, Pakistan and India.

Other Soviet moves would follow, he said, if there was no response to the Moscow-supported Vietnamese invasion of Cambodia. Teng said that "sanctions" are necessary against Vietnam but added that Peking would act "prudently" on the issue.

"Once we say we will do something, we will do it," he added with emphasis during a question session at the Japanese parliament.

Prime Minister Masayoshi Ohira, who also met privately with Teng said he did not think that the Chinese statement "went beyond the posture they have taken toward Vietnam before." In a later meeting with former prime minister Kakuei Tanaka, Teng spoke about a severe punishment of Vietnam.

"China is considering taking an appropriate counteraction even if such an action involves some risk," Teng was quoted by Japanese officials as saying.

The vice premier arrived here yesterday from Seattle, tired and suffering from a cold, on what was described by the Japanese as an "unofficial" visit.

During his meeting with Fukuda, Teng reportedly made a point of explaining differences that cropped up between himself and President Carter, although he described his visit as a success and said that certain differences were to be expected.

According to officials who briefed reporters later, Teng did not elaborate on what "sanctions" against Vietnam he had in mind but his remarks raised again the threat of a military retaliation for Vietnam's massive assault in Cambodia, where the China supported government of Pol Pot has been routed to the countryside.

China has massed between 10 and 12 divisions on its border with Vietnam and the two countries have traded protests about border violations. The United States has urged Teng to be cautious about Vietnam for fear of igniting a major war.

He reportedly told his hosts today that the Soviet Union is using Vietnam in the same way it has used Cuban troops in some African nations and he said that "if we do nothing about the Cambodian situation" the Soviet Union will make similar moves elsewhere in the world.

He told Fukuda, in a separate meeting, that he had informed President Carter that China would not take any "unreasonable action" against Vietnam but added, "Once we decide in our minds, we are not afriad of any dangers."

Teng also appealed in a low-key way for Japan to continue to show disapproval of Vietnam's military action. Japan at first threatened to cancel foregn aid to Vietnam, but subsequently announced it would merely suspend certain contributions for a while. Japan has also supported the position of the Association of Southeast Asian Nations, which called for the removal of foreign troops from Cambodia.

Teng thanked Ohira for both moves and said he hopes Japan will "keep going on this road."

Japanese officials earlier had expressed concern that Teng might attempt to draw Japan into an anti-Soviet alliance, using Cambodia as a kind of test of loyalties. Japan, which is trying to mend its own fences with the Soviets, let it be known it would not participate. Before Teng's arrival, Japanese officials carefully explained his was an "unofficial" visit He is staying in a Tokyo hotel, not in government guest quarters.