WASHINGTON, Oct. 18—The United States expressed concern today over the heightened tensions and build‐up of opposing forces along the Indian-Pakistani border.

Charles W. Bray 3d, a State Department Spokesman, said that the United States was urging both India and Pakistan to show restraint in the situation and was practicing “a form of preventive diplomacy” with other nations as well.

Among the nations reached by American diplomats, officials said, were the Soviet Union, France and Britain.

The United States Government acted a day after it was reported that the President of Pakistan, Agha Mohammad Yahya Khan, had proposed that forces be withdrawn from both sides of the borders between his country and India.

According to the official Associated Press of Pakistan, President Yahya Khan offered to pull his troops back from defensive positions along the borders if India would withdraw her forces and cease what he termed infiltration and other hostile acts. Pakistan has accused the Indians of assisting the Bengali separatist guerrillas in East Pakistan. The report said that the Pakistani leader made his proposal during a meeting in Iran last week with the Soviet President, Nikolai V. Podgorny.

Through the officials in Washington refused to disclose the size of the military buildups along India's borders with East and West Pakistan, they indicated that they were sizable and exacerbated the situation.

“We've been concerned over the reports of heightened tensions in the subcontinent, including what appears to be build‐ups of forces on both sides in the border area,” Mr. Bray said.

“We have been and continue to be in touch with both Governments with a View to urging restraint by both sides in the situation,” he said. “We are also in touch with other Governments on this matter as well.”

Yahya's Proposal Underlined

Mr. Bray, indicating that the United States had no specific peace plan’ for the area, said that “we would support any measures that would have the effect of reducing tensions.”

The other officials‐drew attention to the report of President Yahya's withdrawal proposal.

They also noted a statement attributed to the Indian Defense Minister, Jagjivan Ram, who said that if India were attacked, she would not withdraw from any Pakistani territory her army occupied.

“If war is thrust on us by the Pakistani military junta, our forces will march ‘forward and occupy their cities, and this time we will not withdraw from the occupied territory come what ,may,” Mr.., Ram was quoted as saying.

Asserting that India would not pull, back from the border until the dispute in East’ Pakistan had been resolved, he said, “India will not submit to world pressure in this regard.”

Millions of refugees have crossed into northeastern India and put strains on her resources. So far the Indian Government has refrained from giving formal recognition to the East Pakistan secessionists—but Prime Minister. Indira Gandhi is believed to be under heavy pressure from Hindu nationalists to do so.