Pacifico A. Castro, acting foreign minister of the Philippines, opened a counterattack on critics of his government here yesterday by assuring members of Congress and administration officials that "fairness, honesty and peace are guaranteed" in the upcoming presidential elections.

His three-day private visit, punctuated with media appearances, is part of an effort by the Philippine government to defuse international criticism surrounding preparations for the Feb. 7 balloting, in which President Ferdinand Marcos is seeking his fourth reelection in 20 years. There have been repeated charges, including recent allegations from senior Philippine church officials, that the potential exists for massive fraud in the election.

Castro said he carried a personal letter from Marcos to President Reagan and hoped to deliver it in person although White House spokesman Larry Speakes said no meeting was scheduled. Other Philippine officials said the letter contained Marcos' personal assurance to Reagan that the Feb. 7 election would be free and fair.

Castro's trip, which includes meetings today with Secretary of State George P. Shultz and Reagan national security affairs adviser John M. Poindexter, was arranged in part by the Alexandria public relations firm of Black, Manafort, Stone and Kelly. The company registered with the Justice Department in November as an agent for the Chamber of Philippine Manufacturers, Exporters and Tourism under a $950,000 one-year contract.

Philippine officials have said repeatedly that the rising chorus of U.S. criticism of the Marcos government is the product of a "disinformation" media campaign in the United States, which the new public relations effort is apparently designed to counter.

Castro also told a news conference that there is "not a single iota of evidence" in charges being aired before a House subcommittee this week that Marcos, his wife, Imelda, and other members of the Philippines' ruling elite have invested heavily in U.S. real estate.

He said hearings on those charges, which resume today, were "definitely" timed so as to influence the Feb. 7 election. "This is not an issue" in the Philippines, he said.

However, Marcos' opponent, Corazon Aquino, has frequently charged the Marcos government with corrupt practices and "crony capitalism." A General Accounting Office team is in the Philippines probing accounting methods used to keep U.S. foreign aid from being diverted to private uses, and is expected to report at the end of February, State Department spokesman Marvin Kalb said.

Kalb said previous audits have found no misappropriations. "The administration is not aware of any evidence that would directly or indirectly link U.S. aid dollars to overseas investments by the Marcoses," he added.

A federal grand jury in Alexandria has been probing charges of possible fraud and kickbacks to Philippine military officials involving $35 million in U.S. military communications equipment contracts. No indictments are expected before the election.

Castro, 53, an outspoken attorney, also defended his government's decision to keep all foreign observers and journalists at least 150 feet away from polling places. He said poll watchers inside every voting area will include members of opposition and civic groups who will be "breathing on the necks" of election officials to keep them honest.

"The chairman and the senior poll clerk are usually public school teachers. And in the Philippines since most of the public school teachers are women, you can be sure that they will protect the integrity of the process in the same way they defend their honors," he added.

In an interview, Castro said, "Foreigners have always been a source of confusion, division and disorder" at Philippine elections and needed to be excluded to keep procedures orderly.

Rep. Robert G. Torricelli (D-N.J.), one of two House Foreign Affairs Committee members who met yesterday afternoon with Castro, said later he had withdrawn his request to be part of any official U.S. delegation of observers at the election because the distance requirement would prevent any judgment on the fairness of the election. "There is too great a risk of our being used for purposes with which we may not agree," he said.

During the interview, Castro said U.S. policy-makers displayed an "arrogant attitude" toward his country in demanding domestic reforms as a condition for continuing U.S. aid.

"Your foreign policy establishment can be in agreement on that, but it can also be wrong," he said. He added that the Philippines survived many years without U.S. aid and without U.S. bases and could do so again.