BUENOS AIRES, Argentina (AP) _ President Raul Alfonsin said Tuesday only ''a fool could ignore'' the simmering unrest in the military, and he said he made no deals to end a four- day insurrection.

The last military installation taken over by the rebels, an infantry regiment 60 miles west of the capital, was to be turned back to the government Tuesday.

Rebel leader Col. Mohamed Ali Seineldin surrendered Sunday, ending the third military insurrection in 20 months. It was the worst threat to Alfonsin's civilian government since it replaced a military dictatorship in 1983.

Seineldin was released to direct the dismantling of his Villa Martelli arsenal Monday before formally relinquishing command. He was taken to a military garrison in Buenos Aires for questioning.

Most of the estimated 500 rebels returned to their units, and ''an investigation will take place to clear up who is responsible, and they will be punished,'' said Defense Ministry spokesman Faustino Altamirano.

The unrest began Thursday when 63 coast guardsmen robbed an arsenal and deserted their base. They were imprisoned Tuesday at the suburban Campo de Mayo army base for questioning.

There was widespread support for Seineldin or attempts to incite troops at other bases.

Alfonsin has said since Sunday the insurrection was resolved by negotiation, but contended the government did not concede to any rebel demands.

Only ''a fool could ignore'' the fact that military unrest continues, but ''the bulk of Argentina's armed forces'' believes in democracy, he said, attributing the insurrection to a ''Messianic'' minority.

Rebels demanded an end to the prosecution of officers for human rights abuses committed during the 1976-83 dictatorship, wholesale changes in the military hierarchy, and better pay and equipment.

''The convincing and persuading took so long precisely because no condition was accepted,'' Alfonsin told leaders of a farm cooperative. ''A dialogue of more than two hours (is better than) a battle, even if it lasted just five minutes, which could have cost Argentine lives.''

Alfonsin denounced critics who have wondered aloud whether a secret deal was made. He called them ''vampires ... who apparently feel sad because solutions were arrived at without the spilling of blood.''

Doubts stemmed from the unwillingness of government troops to fire on the rebels, the failure to disarm and arrest rebels following their surrender Sunday, and the maintenance of army bases in rebel hands after the government declared the mutiny over.

Argentines also remember that following the April 1987 insurrection led by Lt. Col. Aldo Rico, many top generals were retired, and legislation was passed that limited the prosecution of officers for human rights abuses.

Alfonsin also declared then that rebels had surrendered unconditionally. Rico, also behind a January mutiny, has been discharged from duty and jailed.

Defense Minister Horacio Jaunarena on Wednesday was to brief the Senate, where opposition Peronist Party members expressed doubts on how the insurrection was resolved.

Even members of Alfonsin's Radical Civic Union were skeptical.

Alfonsin said unrest is based in soldiers' desire for recognition - not censure - that they acted on the public's behalf in curtailing the kinappings, bombings and assassinations by leftists in the 1970s, he said.

While his government will not endorse illegal acts taken by security forces, Alfonsin said he recognized ''there was a struggle (in the streets) that was almost a war, and it was necessary to recover the authority of institutions of the nation.''

A government report said 9,000 Argentines were kidnapped and presumed killed by the officially sanctioned security forces. Five junta members, including former military Presidents Jorge Videla and Roberto Viola, were convicted by a civilian court of human rights abuses in 1985.