A majority of Americans believes that Corazon Aquino was denied victory in the Feb. 7 Philippine presidential election by cheating on behalf of incumbent Ferdinand Marcos, and 7 in 10 advocate suspending U.S. military and economic aid to the Philippines if Marcos stays in office, according to a Washington Post poll.

However, the results of the poll, conducted Sunday while the split between supporters of Marcos and Aquino was reaching crisis proportions, indicate that Americans are much more reluctant to have the United States take other measures to force Marcos out.

Fifty-nine percent of the respondents said they had been following events in the Philippines closely or fairly closely. Of those who said they had some knowledge of the situation, 45 percent said the United States should try to persuade Marcos to resign, while 46 percent were against U.S. involvement.

Among people who said they had not followed the election and its aftermath, 17 percent favored a U.S. effort to pressure Marcos to resign, while 62 percent opposed such active U.S. involvement.

On the question of how they viewed the election results, 56 percent of the respondents said they believed Aquino would have won if the ballots had been counted fairly, while 11 percent said they believed Marcos was the winner. The other 33 percent had no opinion or said they could not decide who had won.

In regard to U.S. aid, 1 in 10 respondents said the United States should continue assistance to the Philippines if Marcos remains president, while 7 in 10 favored a suspension of aid. The others expressed no opinion on the subject. The idea of suspending aid was endorsed by 77 percent of those who had followed the election results and 62 percent of those who said they had paid little or no attention to the situation in the Philippines.

Those polled were reminded that the United States has two strategically important military bases in the Philippines. But only 18 percent said the United States should seek to protect those bases by supporting Marcos; 60 percent said the United States should oppose Marcos because supporting democratic values is more important than the risk of losing the two bases. Twenty-two percent had no opinion on these questions.

Half of the respondents approved of President Reagan's approach to the Philippine situation, while 26 percent said they disapproved of U.S. policy; 24 percent said they had no opinion on the matter.

Among respondents identifying themselves as Republicans, 60 percent endorsed Reagan's approach, 19 percent did not and 21 percent said they had no opinion. Respondents who said they were Democrats gave Reagan a 42 percent approval rating and a 33 percent disapproval mark; 25 percent said they had no opinion.

In the case of both parties, the approval rating for Reagan's policy toward the Philippines was lower than the 65 percent approval rating registered in recent polls for his overall handling of the presidency.

The Post poll was conducted by telephone in the continental United States on Sunday. In all, 1,008 persons, selected at random, were interviewed. The sample was adjusted to conform to Census Bureau figures for the overall population with regard to age, education, race and sex, and theoretically is subject to a margin of error of about 3 percentage points. Figures based on large subgroups, such as those who have followed the situation in the Philippines, have a slightly higher margin of sampling error.