The nation's top business leaders Friday offered an upbeat assessment of the economy, predicting balanced, moderate growth this year.

In many respects, the economic forecast by the Business Council, composed of 61 executives from the nation's largest corporations, was even rosier than the one offered at the group's last meeting just before the October stock market crash."Our consultants are feeling rather good about the economy. They feel better than they did six months ago," said John S. Reed, chairman of Citicorp. The council's economic report reflects a consensus of views held by the chief economists of member corporations.

They predicted that the economy, as measured by the gross national product, would grow at an annual rate of 2.4 percent this year and 2.1 percent in 1989.

When the executives last gathered for their semiannual meeting at this mountain resort, they were expecting somewhat better GNP growth, 3 percent this year. However, the latest forecast shows more moderate inflation and lower unemployment.

Consumer prices are seen rising 3.9 percent in 1988 and 4.6 percent the next year, compared with 4.2 percent in 1987.

The executives said unemployment, which was 5.4 percent in April, would remain under 6 percent through 1989.

Reed said the mix of economic growth expected this year is healthier than the 3.8 percent growth in 1987. The economy in 1988 will rely less on consumer buying and a buildup in inventories and more on improved exports and higher spending by businesses on new equipment, he said.

While Reed stopped short of saying the stock crash was good for the economy, he said, "There were certainly good aspects to it."

It relieved a buildup of tension in financial markets and gave the world's central bankers room to lower interest rates, he said.

"The economy and our businesses are doing quite well in spite of that problem," IBM Corp. Chairman John F. Akers said, referring to the crash. "No one is talking about that anymore."

But some executives said there was a feeling that the economic outlook was almost too good to be true.

Edmund T. Pratt Jr., chairman of Pfizer Inc., said the federal budget deficit and the trade deficit remain serious concerns.