President Corazon Aquino, saying she is determined to "exhaust all efforts" to achieve peace through negotiations, today named two close political associates to talk with communist insurgents.

Aquino announced the appointment of Agriculture Minister Ramon Mitra and former senator Jose W. Diokno at a news conference and said they will meet soon with a Communist Party team in "talks for a cease-fire" in the long-running and increasingly bloody civil strife.

In announcing the move, a fulfilment of her campaign promise to negotiate with the insurgents, Aquino ruled out acceptance of a coalition government, a central demand of the rebels. She seemed to take pains to limit public expectations for success in the talks. "There are some people among the insurgents who will never cooperate with the government," she said, "but I would like to exhaust all efforts to achieve peace."

Yesterday, top Philippine officials were quoted as telling Secretary of State George P. Shultz that there is no basis for "a substantive negotiation" with the rebels because their demands are nonnegotiable. Nevertheless, both government and insurgents seem ready for the talks, each side hoping to gain from the holding of discussions.

Defense Minister Juan Ponce Enrile, who met with Aquino and the two government negotiators before the public announcement, said in an interview today that the strategy is "to use the popularity of Mrs. Aquino to win those rebels who are win-able" and, at the same time, "maintain the erosion of their political support without prejudice to a continuation of our military effort, in order to keep the pressure on them."

Enrile expressed doubt about achieving a cease-fire, saying it would be difficult to know when the rebels actually are complying. He said it would be "impossible" for government forces to "raise the white flag" by withdrawing from the countryside, as the rebels demand.

A key aim of the negotiations, Enrile indicated, is to diminish the "mass base" of active rebel supporters, which he estimated at 1 million to 2 million people dispersed throughout the country. Reversing the loyalties of the support group, which provides food, money, housing and intelligence to the insurgents, would not end the rebellion by an estimated 22,500 armed guerrillas, but would greatly weaken it, Enrile said.

For their part, the communist leaders are reported to believe that their cause can gain recognition and legitimacy through the negotiations, and may win some new adherents.

The outlawed Communist Party of the Philippines has named Saturnino Ocampo, a former journalist, as its negotiator, and Aquino indicated today that others have been designated whose names have not been revealed. United Press International quoted an unnamed source close to the party leadership as welcoming the government appointments and saying that they are "logical" men to handle the talks.

Mitra, 58, was an intimate friend of the president's assassinated husband, Benigno Aquino, and is considered a centrist in the Philippine political spectrum.

Diokno, 64, was a local opponent of former president Ferdinand Marcos and a leading human rights advocate who in recent years has been known for his opposition to the U.S. military presence at Clark Air Base and Subic Bay Naval Base. After Marcos was ousted, Diokno was named head of a government commission to investigate abuses by the Philippines military during the prior regime.

Both Mitra and Diokno were jailed by Marcos along with Benigno Aquino in the initial period of the 1972 martial law crackdown on the political opposition.

Aquino also said that she asked Shultz yesterday to ease restrictions on the use of U.S. military aid to the Philippines, so it can be used for general budgetary support of the armed forces. Aquino's government has cut its military budget 14 percent in the current year as part of its austerity program.

In Washington, the House subcommittee on Asian affairs Thursday authorized an extra $250 million in aid for the Philippines for the fiscal year that ends in September, despite concerns that it would exceed budget constraints.