President Reagan sent special envoy Philip C. Habib to Central America yesterday in what aides said was an attempt to dramatize U.S. diplomatic efforts when the administration is at least 30 House votes short of obtaining a $100 million aid package for the Nicaraguan rebels.

Asked whether he was using Habib's mission as "a cover" for his attempt to obtain military aid for the rebels, Reagan replied that critics of his proposal "have been making ridiculous noises for a long time, and that's one of the most ridiculous."

As he saw Habib off on the White House driveway, the president added, "Nine times we have tried to persuade the Sandinista government to enter into negotiations and nine times we've gotten nowhere."

Earlier, State Department spokesman Charles Redman announced that the president's package of $70 million in military aid and $30 million in humanitarian aid "in no way changes the rules" to permit the Central Intelligence Agency to dip into contingency funds and provide additional aid for the rebels, known as contras.

The announcement was a response to the concern of some House Democrats that the aid request would allow the CIA's secret contingency reserve funds to flow to the rebels without any control by Congress.

These developments occurred as new offers of compromise came from House Democrats and Senate Republicans while the White House and House GOP leaders appeared to stiffen their resistance to anything less than the $100 million aid package.

Senate Majority Leader Robert J. Dole (R-Kan.) said he had sent White House chief of staff Donald T. Regan "information on what may be the basis" of a compromise. He declined to give details, but administration sources said it involved delaying military aid for two or three months while diplomatic efforts attempted to prod the Sandinistas into direct negotiation with the contras.

In the House, Rep. Ike Skelton (D-Mo.) sent Reagan a letter, signed by three other swing Democrats, proposing that Congress approve the package but delay sending offensive weapons for 90 days. This would give "negotiations one last chance," he said.

During the 90-day period the contras could be supplied with defensive weapons, such as shoulder-fired anti-aircraft weapons, under terms of the Skelton proposal, which is taken seriously by administration strategists. Last year Skelton was chief architect of a congressional compromise approving an administration plan to produce chemical weapons.

Despite such manuevering, administration and congressional sources said the president's package appeared headed toward defeat. House Speaker Thomas P. (Tip) O'Neill Jr. (D-Mass.), predicting defeat and opposing any compromise, said "the people of America will win" when the House votes on the issue next Wednesday or Thursday.

Administration strategists began the week believing they could win if they converted 20 undecided Republicans, mostly from the East and Midwest, and 20 undecided Democrats, mostly from the South and West. The administration count yesterday showed only a gain of five in each camp.

Redman's announcement that the administration would not use contingency CIA funds to augment aid to the contras was an attempt to erase a barrier that arose during testimony before the House Intelligence Committee.

Rep. David E. Bonior (Mich.), chairman of the House Democratic caucus committee on Nicaragua, said he was pleased with the statement. "They got caught with their hand in the cookie jar . . . but now I think we can get on with the debate," he said. Rep. Michael D. Barnes (D-Md.) said he still found administration assurances insufficient.

The confusion continued yesterday as administration officials tried to demonstrate a willingness to hear congressional proposals while at the same time proclaiming a determination not to compromise.

White House spokesman Larry Speakes said, "We're not interested in anything short of getting the president's package approved, without conditions."

Emphasizing this approach, the White House canceled a scheduled presidential meeting with Senate Foreign Relations Committee Chairman Richard G. Lugar (R-Ind.) and Sen. Sam Nunn (D-Ga.), a key moderate. "They don't want to send signals about compromising," said a Lugar aide.

However, Reagan refused to rule out the possibility of a 60- or 75-day delay in the military aid in his answers to reporters' questions on the White House driveway. "We're continuing to talk about all possibilities like that," the president said.

Lugar, who supports the administration measure but believes a compromise will be necessary for congressional enactment, canceled a committee meeting today that had been scheduled to vote on the aid package. Aides said this meant that the committee would not have approved the request.

House Republican leaders remained adamantly opposed to any compromise, and congressional sources said that House Minority Leader Robert H. Michel (R-Ill.) told Dole that he wanted the House to vote first if the Senate was inclined to compromise.

Debate is scheduled to begin in the Senate next Monday, but a vote is not expected until the following week. If the package fails in the House and passes the Senate, administration officials said the president will try to bring the Senate version back before the House.

Reagan, who will attempt to rally public support in a nationally televised speech Sunday night, emphasized yesterday that Habib is seeking regional support for peace efforts in his visit to El Salvador, Guatemala and Honduras. In Guatemala, Habib also will meet with Costa Rican President-elect Oscar Arias, who has opposed military aid to the contras.

The president said that Habib wasn't going to Nicaragua because he hadn't been invited there but that "if anything comes up which would show there might be any prospect or profit in doing that, I am sure he would make that decision."

Today Reagan will stress his contention that Nicaragua exports revolution. Officials said the president will appear at the State Department with a defector from the Sandinista government and a former commander of leftist rebels in El Salvador to display weapons purportedly smuggled to guerrillas by the Nicaraguans.

The House Arms Control and Foreign Policy Caucus, in a report prepared for release today, says that 12 of 13 members of the contras' military high command are former officers of ousted dictator Anastasio Somoza's National Guard. A recent contradictory report, released by Lugar, listed leaders of nonexistent "ghost commands" to reduce the apparent National Guard involvement, the study said.