The Heritage Foundation, a conservative research organization, is raising money with a letter of endorsement from presidential adviser Edwin Meese III, and telling potential donors they can meet with top White House officials if they contribute at least $1,000 to the group.

In a mailing that began last month, the nonprofit tax-exempt foundation has asked 5,000 handpicked conservatives to join what it calls the "President's Club" for "a series of meetings . . . with the most senior members of the administration and Congress."

In exchange for a tax-deductible donation of $1,000 or more, foundation President Edwin J. Feulner Jr. says in his fund-raising letter, "you will be provided with an access to Washington policy makers which cannot be had at any price. I have no doubt that you will find your membership fee returned to you many times over . . . .

"Ed Meese told me that he is very anxious to see the President's Club get off the ground," Feulner says in a postscript. "I assured him that I would keep him informed of our progress. Please let me know that you accept your membership so that I can tell him as soon as possible."

In an accompanying letter on White House stationery, Meese tells Feulner that "I am enthusiastic about the establishment of the Heritage Foundation President's Club." Calling it "a vital communications link" between the White House and those who support President Reagan, Meese says that "this administration will cooperate fully with your efforts."

Meese said yesterday that he had not been told that his letter to Feulner would be used to raise money for the Heritage Foundation. "But I have no objection to it. They've been very helpful to our administration, providing materials to us and so forth," he said.

Meese declined to say whether he is concerned that the foundation is soliciting contributions by promising access to top administration officials. "I'd want to see precisely what they said in the letter before making any evaluation," he said. "But we meet with people of all viewpoints."

Attorney Sheldon S. Cohen, who was Internal Revenue Service commissioner in the Johnson administration, said he was distressed by the growing number of groups that are charging people for meetings and conferences with Washington officials. "They're selling access to important people for private gain," he said.

In an interview, Feulner said: "A letter of endorsement is something that every other group around town uses when someone says something nice about them. In the political process, people tend to endorse or work with groups that they're familiar with or feel comfortable with.

"Meese doesn't say give money to the Heritage Foundation," Feulner said. "He's endorsing the program, much as I suppose he endorses the alumni program at his college or university, because it's something he believes in."

Meese has been quite active in speaking to outside groups, from business leaders in San Francisco to a Washington Post luncheon two weeks ago. Meese spoke to about 35 Heritage Foundation members at the University Club here in September, and was the featured speaker at a similar foundation gathering in Chicago last spring.

Feulner said he and Meese are "old friends" and that Meese signed the letter, which probably was drafted by the foundation, at Feulner's request last October. He said this was no different from "George McGovern writing a fund-raising letter for a liberal group when he was in the Senate."

Feulner said up to 50 Heritage members would be invited to discuss general policy matters at two or more meetings in Washington each year, but that they would not lobby officials about specific issues.

"The chairman of the board of a major Fortune 500 company can probably have access to just about anyone," Feulner said. "We're trying to reach the little guy who has no way of seeing these people face to face and getting a feel for them."

President Johnson had his own select group of $1,000 contributors, which also was called the President's Club, but this was a Democratic campaign fund-raising group. Johnson came under criticism when his administration approved a construction project and dropped an antitrust suit against two firms whose executives had given $1,000 to his club.

Feulner said the Heritage Foundation raises 43 percent of its income by sending out 2.5 million pieces of direct mail a year, which has yielded about 120,000 active contributors. The foundation plans to spend $7.2 million this year on academic studies and publications to further its goal of "free enterprise, limited government and a strong national defense." Leon Levine, an IRS spokesman, said that such tax-exempt groups are barred from devoting a "substantial" part of their activities to lobbying or influencing legislation, but that defining the term "substantial" has been a difficult legal question. He said such groups are prohibited from intervening in any political campaign for public office.

In his letter, Feulner says Meese believes that "key conservative activists across the country must be briefed on the conservative program--firsthand, by top policy makers--so they can fight the Liberal tactics of distortion and propaganda being used against the president."

Feulner said he would not have arranged these meetings under the Carter administration because "our constituents would not be as interested in a meeting with Hamilton Jordan or Midge Costanza. And we would probably not have been in a position to even make an offer like that."