President Reagan is considering a suggestion to send a special envoy to South Africa to discuss the tense situation there with President Pieter W. Botha, White House spokesman Larry Speakes said yesterday.

As pressure continued to mount on the administration to take action to show displeasure with Botha's imposition last week of a nationwide state of emergency, Speakes said sending "some one like Sen. Paul Laxalt" had been discussed at the White House. But he added, "I don't think there's been any consideration given to doing it yet."

Laxalt (R-Nev.), a close friend of the president, was dispatched last October to convey Reagan's concern to then-President Ferdinand Marcos of the Philippines about the deteriorating situation there and to urge him to hold presidential elections.

A Laxalt aide said the senator had heard nothing from the White House about such a mission. He refused to say whether Laxalt would accept if asked to go to South Africa, but administration officials said Laxalt had suggested the mission. The senator is concluding his career in the Senate and considering running for the presidency.

Meanwhile, the administration yesterday expressed "grave misgivings" and "strong opposition" to the House vote Wednesday calling for a total and immediate disinvestment of all U.S. companies from South Africa.

An identical bill was introduced in the Senate yesterday by Sens. Alan Cranston (D-Calif.), Edward M. Kennedy (D-Mass.) and Lowell P. Weicker Jr. (R-Conn.).

Speakes said the administration was opposed to punitive economic sanctions because they would "erode our capacity to promote negotiations in South Africa and would likely further separate an already divided society."

Speakes was unable to point to any administration success in promoting negotiations between South Africa's white and black leaders. But he said there have been "discussions" and that the United States stands a better chance of wielding influence if American business remain in South Africa and "we remain in contact."

"We need to continue our efforts, not break them off by withdrawing our economic presence from South Africa," Speakes said.

A Senate Republican source said the idea of Reagan sending a high-level delegation to South Africa headed by a prominent figure such as Laxalt or Sen. Richard G. Lugar (R-Ind.), chairman of the Senate Foreign Relations Committee, had been "kicking around" for several months.

"But the situation is much different in South Africa than the Philippines," the source said. He noted that Reagan had had a close relationship with Marcos while he has "maybe never" met Botha and in any case had "no special relationship" with him.

In the Philippines, he said, Marcos did not believe Reagan shared the views of other U.S. officials urging him to make reforms. Laxalt was sent to show the president meant business.

In the case of Botha, he said, the White House's views were getting through but the South African leader had decided to ignore them. Botha last week rebuffed an appeal from Reagan to exercise restraint and lift the nationwide state of emergency, according to administration officials.

Staff writer Edward Walsh contributed to this report.