The United States made urgent appeals yesterday both to Vietnam and its ally, the Soviet Union, for a halt of Vietnamese military attacks into Thailand.

Soviet Ambassador Anatoliy F. Dobrynin was called to the State Department for a half-hour meeting in which Allen Holmes, acting assistant secretary for European affairs, asked that Moscow use its influence to stop the raids across the Thai border by Vietnamese forces in Cambodia.

At the same time, the department announced, Morton Abramowitz, U.S. ambassador to Thailand, met with Vietnamese Foreign Minister Nguyen Co Thach, who is visiting Bangkok, to express "the deep concern" of the United States about the threat to Thailand's security and regional peace in Southeast Asia, as well as the disruption of relief programs for Cambodian refugees.

These actions came after Secretary of State Edmund S. Muskie publicly called on the Soviets Wednesday to put pressure on the communist government in Hanoi. Vietnam is Moscow's chief ally in the region, and Muskie said the border incursions would not be possible without Soviet support.

[Muskie, arriving this morning in Malaysia on his first diplomatic trip to Asia, condemned the Vietnamese incursion as "aggression," which he likened to the Soviet invasion of Afghanistan.]

The fighting began Monday, when Vietnamese forces, apparently retaliating against raids by Cambodian insurgents operating from Thailand, crossed the border and occupied refugee camps. Since then, several hundred reportedly have been killed or wounded on both sides.

The situation has caused growing concern here about the security of Thailand, the last remaining U.S. ally in Southeast Asia, and the threat of widening new conflicts in the region.

When Vietnam invaded Cambodia last year and ousted the China-oriented Pol Pot regime, Peking responded by sending Chinese forces to attack Vietnam. The Chinese since have withdrawn from Vietnam, but Peking has warned this week that it will not allow the latest Vietnamese military actions to go unchallenged.

Department sources said the U.S. concern about broadened warfare in Southeast Asia and the consequent increase it would cause in tensions between Moscow and Peking were emphasized in the meeting with Dobrynin. The sources added that Dobrynin promised to relay the message to Moscow but otherwise was noncommittal.

Department spokesman Tom Reston said Thailand has asked the United States for accelerated deliveries of artillery, ammunition and small arms. Reston added that the request is being given priority attention.

Under the U.S. aid program for fiscal year 1980, Thailand is eligible for military sales credits of $35 million, and the Carter administration's fiscal 1981 aid request, now pending in Congress, proposes military sales credits of $50 million to Thailand.

Department officials said total U.S. arms sales to Thailand, including those under the foreign military sales credit program, amounted to roughly $100 million in 1977 and 1978, and increased to $400 million in 1979. They added that total military sales to Thailand this year are expected to be between $250 million and $300 million.

In New York, U.N. Secretary General Kurt Waldheim called for an end to the fighting, saying it posed a threat to thousands of lives.

The Associated Press reported from Bangkok that the Vietnamese foreign minister, Thach, said Vietnamese troops would move against guerrilla concentrations to the south of the Thai border town of Aranyaprathet to stop the repatriation of outsed Cambodian premier Pol Pot's Cambodian followers.

Thach also denied that Vietnamese troops had entered Thai territory, and said the fighting since Monday was deliberately provoked by the Thais to win support for their anti-Vietnam position.