South Africa's white electorate has signaled its resolve not to alter the country's framework of racial separation with a record victory for the National Party in yesterday's election.

But the national elections also passed the mantle of official parliamentary opposition to a party that favors changes eventually leading to majority rule - the Progressive Federal Party.

The lopsided swing to the National Party is a message to the United Nations and particularly the Carter administration that South Africans are determined to resist pressures to alter their racial policies. The United States sharply criticized South Africa's October crackdown against black opponents and the U.N. Security Council voted an arms embargo against South Africa, the first against any member nation.

"South Africans wanted to show they were united against unwarranted and unwanted interference in internal affairs," said Christopher Reneken, who yesterday easily retained his seat in Parliament for the National Party despite running in a district that traditionally votes for the opposition.

The election outcome also means that any changes or "concession" to the politically disenfranchised 19 million blacks, 2.5 million coloreds and 750,000 Indians, will be made within the framework of aparthied, the government's policy of separate development for each race. This means there will be no changes of the kind envisioned by Western and African countries that would lead to an integrated sharing of political power throughout the nation.

"I never held out any false promises to black leaders. Vorster told 5,000 cheering white supporters at his final campaign rally. "I told them ask me for many things, but don't ask me to be represented in my Parliament, because the policy of my party is that you are not represented there."

Barring devastating international economic sanctions or wholesale uprisings of the black population - neither of which is likely - South Africa now faces continued entrenchment of the basic aparthied structures. However, massive discontent and growing politicization of urban blacks, economic harassment from foreign firms and a continued economic slump, may prompt the government to move toward elimination of some discriminatory practices and improvement of the economic conditions of the urban blacks.

A signal of just how far Vorster's party is willing to move on this front will be his appointment of a new head of the Ministry of Bantu Administration and Development. This porttolio is crucial because it deals with the grievances of urban blacks who are the most restless group.

The massive mandate for the National Party also means that a tighter circle will be drawn about internal dissenters to government policies. Because the voters have in effect approved the government's much criticized Oct. 19 rash of bannings and detentions.

With South African generals now talking of preparing for "total war" and government officials declaring that recent bombings are the work of "hard-core terrorists," dampening of dissent can only get harsher. "We don't crack down for the fun of it . . . but we don't want the unwarranted and unwanted militancy of certain organizations inside the country," Rencken said.

Right after the election, Vorster said the two principles of freedom of the individual and the safety of the state are stressed "depending on the circumstances." He pointedly added: "Just as South Africa is situated at the moment, you cannot afford to play with the safety of the state."

The National Party's unprecedented strength - 134 seats in the 165-member Parliament - has led to talk of a "one party state." But the Progressive Party now with 17 seats, hopes to keep up a lively opposition.