President Reagan asked the Justice Department yesterday to determine whether the Voting Rights Act, key provisions of which expire in 1982, remains after 16 years the best way of protecting the political rights of minorityl Americans.

In a letter to Attorney General William French Smith that is Reagan's first presidential statement on the civil rights legislation, he made it clear that he is of two minds about the act and his support for renewal in its current form should not be taken for granted.

Reagan said the 1965 act made "a massive contribution" to achieving political equality for blacks and Mexican-Americans, but he echoed the concern he voiced during his presidential campaign that it imposes unequal burdens on some parts of the nation.

One of the provisions expiring next year requires nine states, mostly in the South, and parts of 13 others to get approval from the attorney general or the U.S. District Court here before making any change in their election laws or practices.

Senate Judiciary Committee Chairman Strom Thurmond (R-S.C.) is among those who attacks the Voting Rights Act for treating the South unfairly; he favors the act's repeal. Another foe of the act, Rep. Henry J. Hyde (R-Ill.), has said: "The time has come for us to recognize that it is outrageous to require local officials to come to Washington to pre-clear [election] laws."

Civil rights leaders have been equally adament that without the prior clearance provision, the voting rights of blacks and Hispanics would slip backward.

Reagan's top aides have said recently that the administration is reviewing the act. Reagan's letter asking Smith to assess the legislation therefore was both a careful straddle of the controversy and a formal reiteration of what his aides have been saying.

"I am sensitive to the controversy which has attached itself to some of the act's provisions, in particular those provisions which impose burdens unequally upon different parts of the nation. But I am sensitive also to the fact that the spirit of the act marks this nation's commitment to full equality for all Americans, regardless of race, color or national origin," Reagan said in language clearly aimed beyond Smith to the public.

"Because my administration intends to maintain that commitment, the question before us in the months ahead will not be whether the rights which the acts seeks to protect are worthy of protection, but whether the act continues to be the most appropriate means of guaranteeing those rights," the president added.

By releasing the letter yesterday, Reagan gave himself a ready-made answer should he be asked about the Voting Rights Act at his news conference today.

Reagan asked Smith to complete the Justice Department's report on the act by Oct. 1.

The Voting Rights Act, which its supporters hail as perhaps the most successful civil rights legislation in U.S. history, has been extended twice -- in 1970 and 1975. It was broadened in 1975 to protect Hispanic-Americans who speak little or no English.

The president's letter was issued on what White House deputy press secretary Larry Speakes called the first day of Reagan's personal involvement in selling his tax program.

Reagan's views have been no secret and he has had frequent contact with members of Congress in recent weeks about the tax bill, but the White House is consciously repeating the pattern that brought Reagan success with his budget-cut proposals and that requires a formal opening of the personal presidential campaign.

Reagan met with Republican House leader Robert H. Michel (Ill.) and Republican members of the House Ways and Means Committee. Michel and the committee's ranking Republican member, Rep. Barber B. Conable Jr. (N.Y.) told reporters upon emerging from the Oval Office that they are concerned that the House Democratic leadership may drag its feet to prevent passage of a tax-cut bill by the Aug. 1 deadline Congress has established.

Reagan also met with a group of Democratic senators, most of whom support his tax proposal and who predicted it will win Senate approval.

On Capitol Hill, Ways and Means Democrats met in their two task forces considering an alternative to the Republican-backed individual and business tax cuts.

In another development, Speakes announced a $1.16 million grant to the city of Atlanta and Fulton and DeKalb counties in Georgia for additional supervision in summer recreation programs as part of the federal assistance to that area in response to the murders of 28 blacks.