An overwhelming majority of Americans supports the military reprisal that destroyed an Iranian oil platform on Monday, despite the widespread belief that the attack will escalate the tanker war in the Persian Gulf and lead to more Iranian terrorist attacks against the United States.

A Washington Post-ABC News overnight survey of 507 adults nationwide also disclosed growing fears that the United States will become involved in a "major military conflict" in the Persian Gulf region in the near future.

Almost three of four respondents -- 74 percent -- said it is likely that the United States will become involved in a "major military conflict" in the Persian Gulf region in the near future. That represents a 14-percentage-point increase since the question was asked in a Post-ABC poll in June.

The survey showed that 76 percent of those interviewed said they approved of the U.S. Navy bombardment Monday that destroyed the Rashadat oil platform, which the Defense Department said Iran had converted into a communications center and staging area for attacks on oil tankers in the gulf. Twenty-two percent said they disapproved of the raid, and 2 percent had no opinion.

Almost two out of three -- 63 percent -- said the raid was an appropriate response to what the Reagan administration has characterized as Iranian acts of aggression. Those incidents included Friday's Silkworm missile attack on a Kuwaiti tanker flying the U.S. flag, as well as a recent attack on a U.S. military helicopter.

Slightly more than one out of five -- 21 percent -- said the American response was not strong enough, while 13 percent characterized the shelling as "too strong" a response. The remainder was undecided.

More than half -- 57 percent -- said the United States is "doing all it should to avoid getting into a war with Iran."

Seven of 10 respondents said they expect the U.S. raid will encourage Iran to sponsor more terrorist acts against the United States. A smaller majority -- 57 percent -- said the U.S. raid will encourage Iran to launch more attacks on American-flagged tankers in the Persian Gulf.

An analysis of the results of the overnight survey and a larger Post-ABC poll completed just before Monday's naval action disclosed general agreement among most segments of the public on key elements of the raid, but apparent confusion about the Reagan administration's policy goals in the region.

The analysis showed that men were more likely than women, and Republicans only somewhat more likely than Democrats, to favor the raid, as well as to support U.S. actions generally in the gulf. More than four out of five men and two out of three women said they supported the attack. More than four out of five Republicans and seven of 10 Democrats said they supported it.

The survey also disclosed widespread support for U.S. efforts in the troubled region. Four out of five respondents agreed that the "United States should maintain a military presence in the Persian Gulf." And two out of three said the area is important enough to U.S. interests to risk war with Iran, a view held by four out of five men but barely half -- 53 percent -- of women.

Slightly more than three of five -- 63 percent -- said they generally approved of the way Reagan is handling the situation in the gulf, and an equal number favored the U.S. Navy escorting reflagged Kuwaiti oil tankers there. Those numbers remained unchanged from the results of a Post-ABC poll conducted last week, but represent increases from surveys conducted this summer and spring.

But more than half of 1,505 persons surveyed before the raid on Monday said the administration has done a "not so good" or "poor" job explaining why U.S. forces are escorting Kuwaiti oil tankers.

A substantial majority -- 59 percent -- disagrees, however, that the United States is trying to do too much with its armed forces in the gulf. That belief is held by seven of 10 men but only half of the women.

About half -- 51 percent -- of all self-described Democrats said they believed that the United States was trying to do too much militarily in the region, but fewer than three of 10 Republicans expressed a similar view.

More than three of five -- 63 percent -- said they had a "great deal" of confidence in the ability of the U.S. military to defend itself in hostile areas such as the gulf, a 10-percentage-point increase since that question was asked in the Post-ABC poll taken immediately before the raid.

The Post-ABC overnight survey was conducted by telephone on Monday evening, and was designed to measure immediate reactions to the U.S. raid. Public attitudes could change significantly, however, as more details of the attack are disclosed, or as new events intervene to alter opinion.

The overall margin of sampling error for a survey of this size is plus or minus 5 percentage points. The methods used to complete interviewing in a single evening, as well as the practical difficulties of doing any public opinion poll, represent additional potential sources of error.

Polling analyst Kenneth E. John contributed to this report.