The White House expressed concern yesterday that public opinion is drifting away from supporting President Reagan's initiatives to fight communism in Central America as the president conferred with two dozen House members on a strategy for winning more aid from Congress for friendly forces in the region.

Several members told Reagan that support for his efforts seemed to be slipping, and Reagan "indicated he was frustrated because the word needs to get out more to the country on what the facts are," said Rep. E. Thomas Coleman (R-Mo.).

Presidential spokesman Larry Speakes told reporters that the members and the White House have detected "some reversals in public opinion," which he blamed on a "negative drumbeat" from administration critics.

Speakes said the "reversals" had come after a favorable response to Reagan's April 27 address on Latin America to a joint session of Congress.

Despite the upturn in public support back then, private polling done for the administration recently has shown that the American electorate remains somewhat skeptical of Reagan's initiatives in Central America, partly out of fear that he would send American troops into the region.

According to Speakes, the president nodded in agreement yesterday when one of the members blamed the news media for the drift in public opinion. After the meeting, Rep. Newt Gingrich (R-Ga.) said the American press is being "used and exploited" by communists in Central America and that the press has made it "very difficult to communicate the problems."

Speakes said some of the congressmen urged Reagan also to undertake a stronger public relations effort in El Salvador to reinforce the administration's point about the need for U.S. aid to fight leftist insurgents.

The 45-minute session yesterday was sought by a group of House Republicans who are planning strategy to support Reagan on Capitol Hill, and a few members who had just returned from El Salvador.

Coleman also presented Reagan with a report by the House Republican Research Committee that claimed that the United States could expect to receive up to 7 million refugees from Central America if the entire region fell to communist forces.

These are the "feet people"--similar to the boat people who fled Vietnam--about whom Reagan expressed concern earlier in the week.

Reagan was also urged by the congressmen to avoid compromising in forthcoming votes on Capitol Hill to restrict his initiatives. Coleman said Reagan opened the session by saying "he needs full funding of his requests for military aid or we won't be able to save El Salvador."

Reagan has asked for $110 million in military aid to El Salvador, but Congress has approved only $30 million. Additional assistance is pending on Capitol Hill.

The administration is fighting an amendment, scheduled for a House vote on July 14, that would eliminate covert military aid to anti-Sandinista forces in Nicaragua and replace it with open assistance to friendly governments.

Meanwhile, Sen. Alan Cranston (D-Calif.), a presidential candidate, said yesterday that he will seek to end military aid to El Salvador unless the Salvadoran government makes a determined effort to end human rights violations.

Cranston said he will offer an amendment to the foreign aid bill to cut off all U.S. military aid within 90 days of enactment of the bill unless "significant progress" is made.

Also yesterday, Supreme Court Justice William J. Brennan Jr. temporarily revived restrictions on travel to Cuba. Acting on a government request, Brennan set aside, at least until Tuesday, a lower court ruling that overturned the restrictions. Brennan asked the Justice Department and challengers to the restrictions to provide more information on the controversy.