A U.S. diplomat under attack by communist members of India's Parliament and the Indian left-wing press has been barred by New Delhi from taking a senior post at the U.S. embassy there.

In retaliation, the United States has informed India that it will not accept the Indian choice to fill the same position in India's embassy here, State Department spokesman Dean Fischer said yesterday.

Fischer said India's rejection of George G. B. Griffin, assigned to be political counselor in New Delhi, is "most unwarranted." Fischer refused to characterize overall U.S.-Indian relations, but they have been strained by the administration's decision to help Pakistan's armed forces modernize and by its view that India aligns itself too closely with the Soviet Union.

Griffin was rejected because of allegations that he gave information about the situation in Kabul, Afghanistan, his last post, to foreign reporters in Delhi and allegations that he had been involved with dissident Bangladeshi groups during a tour of duty in Calcutta 10 years ago, according to Indian officials.

"He would have had a very rough tour," one said. "Politicians and others would have shied away from being seen with him."

Some U.S. officials believe that Moscow, where Griffin also has been attacked in the press, is behind the Indian rejection. Indian officials deny that charge.

In criticizing the Indian action, the State Department issued a statement defending Griffin: "He has had an outstanding career, which has included many difficult assignments. He has acted at all times in accordance with instructions and the norms of proper diplomatic behavior. That this action was taken at a time when Griffin has been a target of a Soviet disinformation campaign makes it particularly regrettable. He is being reassigned to a position of appropriately senior responsibility."

That new assignment has not yet been decided, a State Department official said.

All governments must be formally asked to approve nominated ambassadors, but it is highly unusual for a lower-level diplomat to be blocked from taking a post.

The first press attack on Griffin, 46, came Dec. 4 in the leftist daily Patriot, which accused him of spreading "falsehoods" to the western press about the situation in Afghanistan.

Griffin was the second-ranking U.S. diplomat in Afghanistan from 1979 until early this summer. His wife and daughter lived in "safe haven" in Delhi and the Indian government gave him a multiple entry visa so that he could make frequent visits from Soviet-occupied Afghanistan.

While in India he discussed the Afghanistan situation with western reporters. Soviet troops were meeting stiff guerrilla resistance in Afghanistan and the population was not rallying to the new, Soviet-installed regime.

The Soviet news agency Tass and Radio Moscow quickly picked up the Griffin story from Patriot, according to the State Department. Radio Moscow accused Griffin of slandering the Soviet Afghanistan policy.

On April 29, Pravda carried an item from Delhi quoting an organ of the Communist Party of India accusing Griffin of being a "highly placed Central Intelligence Agency employe" sent from Pakistan to India to coordinate activities of Afghan exiles and U.S. spies, the State Department said. These charges were repeated by the Kabul media, and the U.S. government protested to Moscow.

"The story is, of course, false," the protest said, denying that Griffin works for the CIA. "In view of the obvious falsehood, we can only conclude that it was designed to complicate Indian-American relations," the State Department said. India also was informed at that time that Griffin was not a CIA employe.

The campaign against Griffin continued in left-wing Indian journals, in Moscow and in Kabul.

In early May, a Communist Party member of Parliament, Bhupesh Gupta, asked that Griffin be stopped from talking to reporters and charged that he had taken an anti-Bangladesh stance during his tour of duty in Calcutta. Other members of Parliament began to discuss the case, Indian officials said, and India made its first hints to the United States that Griffin should not be assigned to the Delhi embassy.

Indian diplomats followed up in June with further hints and on July 28 delivered their formal rejection of Griffin, Indian officials said. They told the United States that they based their opposition on information in their possession, but did not spell out the details, the officials said.

"They never fully explained to us why they took the position that they did," Fischer said.

Indian officials said they think Griffin's presence in Delhi would have brought continual left-wing attacks that would have been a constant irritation to U.S.-Indian relations.

The political counselor at India's embassy here is scheduled to depart for a new assignment. Fischer made clear that whomever India first designates to fill that post will be rejected in retaliation for the Indian action against Griffin.