Fed considers a slight rise in US interest rates

''We have not gone as far as we need to go. Probably we will need some further rise in interest rates to get the right results,'' a top United States monetary official says.

By ''results'' he means steady, noninflationary growth of the economy - a slowing of momentum to avoid too rapid a buildup of demand of goods and services.

''Since late May,'' the official says, ''interest rates have moved up considerably - not by the standards of the last three years, but by historical standards.''

Despite higher rates, the economy still booms along, as the latest unemployment and other statistics show. This has led Martin S. Feldstein, the chief White House economist, to forecast third-quarter growth ''in the same range'' as the torrid 8.7 percent pace of the April-June period.

That fast a growth rate has sharpened a debate within the Federal Reserve Board over whether to tighten the credit reins slightly to nudge interest rates a bit higher. Progress against inflation, according to one school of thought, could be endangered if the economy were allowed to grow unchecked at its current pace. So far, a slim majority of the Fed's policy-setting Federal Open Market Committee (FOMC) reportedly favors raising interest rates.

''Tighten now,'' says one monetary official, ''and it may take only a 1 percent rise in interest rates to achieve what we need. Wait six or nine months, and it may take a 2- or 3-point rise.''

A minority within the FOMC - made up of all seven Federal Reserve Board governors plus five presidents of regional Federal Reserve banks - argues against tightening credit on the grounds that inflation should not be a danger for some time to come.

''Oil was a major culprit in the inflation of the 1970s,'' says a senior adherent of this view. ''I do not see oil prices rising in the near future, given conservation and increasing supplies from non-OPEC sources.''

This view would gain strength, experts agree, if Iraq and Iran - two members of the Organization of Petroleum Exporting Countries - end their war and compete to step up oil exports.

''Any new inflation will come primarily from classical excess demand [for goods and services],'' says a member of the FOMC. ''This is not likely to occur, because interest rates, even at their present level, will dampen growth somewhat.''

Moreover, despite the economy's rapid growth rate, there is still a significant amount of unused industrial capacity. Some economists argue that this gives the economy extra running room before the threat of rapidly rising inflation reappears.

The FOMC member foresees the US economy growing at a 3- to 4-percent pace in 1984, considerably slower than current growth figures would indicate.

Consistently, Fed chairman Paul A. Volcker has urged Congress and the White House to trim budget deficits to avoid or at least lessen a borrowing clash between the US Treasury and rapidly growing private demand for money.

Mr. Volcker told Congress before it recessed for the summer that signs of such a clash are already evident. Despite this warning, echoed by Republican economist Alan Greenspan, neither Congress nor President Reagan has taken effective steps to curb budget deficits.

This puts the onus squarely on the Fed to decide how much money to allow to flow through the economy to keep the recovery going and at the same time avoid inflation.

The internal Fed debate takes on new urgency following the news that the nation's unemployment dropped from 10 percent to 9.5 percent in July. This is dramatic good news for jobless Americans, half a million of whom found work last month. But the figures also indicate that the economy is heating up more quickly than had been expected, putting pressure on the FOMC to chart a fresh policy course.