President Reagan has given his tacit approval for the formation of a reelection committee to plan his campaign for a second term, according to White House officials, who said it is the most significant indication yet that Reagan would run again in 1984.

In recent discussions with Republican political strategists, according to one administration source, Reagan raised no objection to the committee's formation so long as he would not be forced to give it his official blessing until after his Far East trip this November.

"The decision has basically been made" for Reagan to seek reelection, said one official. Another official said that if Reagan is planning to retire, he hasn't told even his closest assistants, all of whom now believe he is running again.

Even after the reelection committee is created, however, Reagan would still have the option to pull out if he wished. Under federal election laws, the committee would be empowered to raise and spend campaign funds and would qualify him for federal matching funds for the primary and caucus races.

The Reagan reelection committee, which plans to open its offices in Washington sometime after Oct. 15, will be run by White House political affairs director Edward Rollins, with help from his deputy, Lee Atwater, and from Republican political consultant Charles Black, among others.

James Lake, who was press secretary at the beginning of Reagan's 1980 presidential campaign until he, Black and John Sears, who had been Reagan's campaign manager, were fired the day of the New Hampshire primary, will be press secretary for the 1984 reelection committee.

When the committee opens its doors, officials said, Rollins' White House political affairs office will be closed down.

One Republican strategist familiar with the White House plans said Reagan has talked with aides about the reelection committee's timetable, which is important because of Reagan's November trip to the Far East. If the reelection committee is formed on Oct. 15, Reagan would have 15 days under federal election law to either give it his blessing or disassociate himself from it.

That would mean that Reagan would become a candidate by Nov. 1, just before he departs from his California ranch for the Far East trip.

According to White House officials, the president has expressed his wish that he not become a candidate until after he returns from the Far East the third week of November.

"The president is thinking now in terms of when he's a candidate, and he doesn't want to be until after the Far East trip," one political strategist said.

Officials say Reagan doesn't want the additional political coloration of a reelection committee to which he has given his blessing overhanging his trip. Thus the decision to delay formation of the committee until after Oct. 15 to avoid creating a situation in which Reagan would have to act before the trip.

Reagan's political advisers are operating on the assumption that he will make the formal announcement of his candidacy at the latest possible moment, perhaps in December. In 1980, Reagan was the last of the Republican candidates to make a formal announcement.

According to administration officials, key decisions about Reagan's reelection campaign have already been made in some large states. For example, Sen. Alfonse M. D'Amato of New York has been selected as chairman of the Reagan campaign in his state. Efforts to put in place chairmen in New Jersey and Illinois are also under way.

Today, Reagan returned once again to campaigning, speaking to a luncheon of four Hispanic business organizations at the Biltmore Hotel here. Reagan coupled a salute to Hispanic entrepreneurship with an upbeat review of his economic program. The president, who only two weeks ago decried "special-interest politics," took another plunge into the practice himself today. Before his speech to the Hispanic luncheon, the White House distributed a proclamation declaring "National Hispanic Heritage Week, 1983."

Reagan, speaking to the Hispanic groups today, left few bases untouched. He applauded the "strength and dignity" of Hispanic women. He hailed the "hard work" of Hispanic entrepreneurs. He singled out the generosity of a Hispanic couple who donated $10,000 to a home for orphaned girls in Mexico.

"To every cynic who says the American dream is dead, I say: Look at the Americans of Hispanic descent who are making it in the business world," Reagan told the groups.

On Wednesday, a top official from one of the nation's biggest Hispanic membership organizations, the League of United Latin American Citizens, criticized Reagan's campaign for Hispanic support.

This morning, presidential spokesman Larry Speakes fired back, saying that LULAC is "a highly partisan organization." He added, "I honestly don't think that reflects the rank-and-file" of Hispanic Americans.

Speakes also claimed that Reagan has appointed more than 125 Hispanics to top-level administration positions, and he reiterated Reagan's support for a "strong" bilingual education program that would help Spanish-speaking schoolchildren learn English.

Reagan is scheduled to fly to San Diego on Friday to speak to a Republican women's group.