The prospect of a meeting between President Pieter W. Botha and Nobel laureate Desmond M. Tutu to try to defuse South Africa's racial crisis appeared to collapse today as the president set conditions for the meeting that Tutu said he could not accept.

Botha responded to Tutu's formal request for an urgent meeting, which Botha's press secretary said Friday would be accepted, by indicating that Tutu, an Anglican bishop, could come as a member of a church delegation in three weeks' time and adding a rider that implied that if he did so, he could be assumed to have denounced the black community's civil disobedience campaign.

Botha also warned in a speech today that if the United Nations Security Council continued calling for sanctions against South Africa, as it did in a resolution Friday, his government would consider sending home 1.5 million workers from neighboring African states and severing transport, communications and other links with them.

Observers saw the two developments as an indication that Pretoria was becoming more intransigent as world condemnation of its declaration of a state of emergency eight days ago increased, and that there was now little hope of the government trying to ease the situation by making a concessionary gesture to the rebellious black population.

It seems intent on continuing to try to crush the 11-month rebellion by arresting grassroots activists, especially the leaders of scores of community-based organizations. By tonight 1,215 persons had been detained under the emergency regulations, according to police reports.

Despite the crackdown, sporadic unrest continued today, and the death toll for the eight days of the emergency rose to 19 after police shot a black student demonstrator near Cape Town.

The shooting occurred when police broke up a demonstration march by 1,000 black students through Guguletu township. It was the second day of disturbances in Cape Town, which has been relatively quiet during the unrest, and some observers saw this as an indication that the disturbances might spread to new areas as police crack down in the main trouble spots.

The unrest also showed signs of spreading into the Colored (mixed-race) community, as 4,000 students boycotted lectures, broke windows and overturned furniture at the University of the Western Cape for Coloreds near Cape Town.

In an American television interview, Tutu called attention to contrasts in the Reagan administration's foreign policy, alluding to U.S. sanctions against the Sandinista rulers in Nicaragua: "If the Reagan administration were to apply the policy it applies against Nicaragua to South Africa, then apartheid would end; if not overnight, it would certainly be dealt a death blow."

Botha's turnaround on the Tutu meeting surprised observers. Some were speculating tonight that Botha might have encountered resistance to the meeting within his ruling Afrikaner National Party, where Tutu is regarded with special dislike because of his denunciation of its apartheid policy of segregation as un-Christian.

In Washington, a State Department spokesman said the Reagan administration was "disappointed" that Tutu's request was denied. "We believe South Africa's internal situation is such that a meeting between the state president and important black leaders is imperative," said spokesman Charles E. Redman. "Dialogue . . . is the only way out of the crisis that South Africa faces."

Redman said he was "hopeful" that the Aug. 19 meeting date might be "the beginning of a dialogue."

Tutu himself, clearly angered, accused the president of "playing political games" with him.

"The situation in our country is too serious for that," Tutu said. "I made my offer to meet the president because I am deeply concerned about what is happening in our country."

Despite his anger, Tutu left the door open for a meeting and also urged Botha to meet some other leader with credibility in the black community if he found him unacceptable.

"It may be that he has an animus against Desmond Tutu, though it seems a very great sadness that Tutu can go into the Oval Office in Washington and into the Elysee Palace in Paris but not into their equivalent in his own country," the Nobel laureate said.

"That demonstrates very clearly the crisis in this land," he added.

Botha's suggestion that he would see Tutu in three weeks and then as part of the church delegation appeared to be a rollback from a statement by his spokesman that the president would see the Nobel laureate at his "earliest convenience."

Botha added another condition by saying in his response to Tutu, which was later made public, that he was prepared to meet anyone "who denounces the use of violence and civil disobedience."

This added a condition not mentioned before by the president. Tutu has repeatedly denounced the violent trend that the unrest has taken in some areas, particularly the killing of blacks seen as collaborators in the apartheid system, but he strongly supports civil disobedience as a strategy for trying to force the government to dismantle apartheid, arguing that it is the only alternative to violent struggle.

Later in the day, Botha said he had ordered a survey of the estimated 1.5 million foreign blacks working in the country so the government can prepare for their explusion if other nations join France in imposing sanctions to protest the state of emergency.

About 500,000 of the foreign blacks work in the country's gold and coal mines; others are employed in agriculture and manufacturing.