U.N. Ambassador Andrew Young, answering a last-minute invitation from Uganda's provisional president, today made a brief stop here to confer with the head of this beleaguered government.

The 2 1/2-hour visit was seen as an effort by Young to lend diplomatic support to the strained Tanzanian-supported government of President Godfrey Binaisa, Uganda's second president in little more than four months.

Young, his wife Jean, his 6-year-old son Andrew III and 28 businessmen and reporters did not go into Uganda's capital city, Kampala, where there have been a host of night-time killings and reports of thuggery. The Young party, all part of a U.S. trade mission to Africa, were fed roast chicken and beef on the well-manicured lawns of Entebbe's state house, in sight of the country's international airport.

Binaisa, a blunt-spoken lawyer, said during Young's visit that he had appealed to fellow British Commonwealth members, at their recent summit in Lusaka, Zambia, for a security force. He added that he did not expect any help from them, however, as he had not received any response.

With Tanzanian soliders in Uganda, Binaisa said, law-and-order problems are "serious, but not alarming." Britain is training a group of police instructors in London, he added.

"I think we've made a wonderful recovery," Binaisa said of Uganda since the defeat of Idi Amin. "It would be a miracle if we didn't have the few incidents we have had."

Both Nyerere and Binaisa had argued, however, that Tanzanian soldiers would have to remain in Uganda until a new police force and army are trained. Binaisa said today the training of the two forces could take as long as a year.

The trade mission stopped at Entebbe after leaving Dar es Salaam, Tanzania, where Young met for 90 minutes with President Julius Nyerere, the Ugandan president's strongest supporter.

At a press conference before the trade mission left Dar es Salaam, Nyerere said he had no regrets about invading Uganda and toppling Amin, but he added that he would like to withdraw his soldiers.

"They cost us a lot of money," said Nyerere reflectively, (but) we don't have a timetable" for withdrawing Tanzanian soldiers from Uganda. "We would have liked to pull them out yesterday, not tomorrow," he said.

Tanzania's continued presence in Uganda has been a source of controversy among African states since Amin fled the country ahead of Tanzanian troops last spring. Tanzania had invaded Uganda in retaliation for an Amin-initiated attack on Tanzania in October 1978.

One Ugandan reporter asked Young why black Americans had come to Uganda during Amin's reign and then returned to the United States to denounce as untrue the stories about atrocities under the dictator.

"They were gravely mistaken," Young replied. "We tend to rally and support anyone white people attack" as a reflex action, Young said.

"They may have been taken in by Amin," he added.

On another matter, Binaisa said Uganda's economy, transport network and communications, which were allowed to deteriorate under Amin, are in great disrepair. Asked what he had been able to accomplish during his three months in office, Binaisa said not much.

"The international community has not been forthcoming to the extent I expected them to be" with financial assistance, he said. "You've got to give me time."

Binaisa then presided over the signing of an agreement with American businessman Thomas Wood, who is to supply the Ugandans with approximately $60 million worth of leased trucks and road graders. The vehicle leases are to be financed by the African Development Bank and the U.S. Export-Import Bank, to help Uganda get its coffee crop ready for export.

"We're prepared to help them immediately get the coffee crop out," said Export-Import bank chairman John L. Moore.