U.S. economic growth cooled off in the second quarter, coming in lower than economists had been expecting.

The U.S. Commerce Department said gross domestic product, the country’s output of goods and services, grew at an annual rate of 3% for the second quarter. That was down from the 4.5% seen in the first three months of 2004.

Economists had been expecting annual growth of 3.8% in the second quarter.

The growth rate for the April-to-June quarter was the slowest since the first quarter of 2003, when the economy expanded at a weak annual rate of 1.9%.

Consumer spending, which accounts for about two-thirds of economic activity, grew at an annual rate of only 1% in the second quarter, the slowest growth in three years.

U.S. real GDP expanded at a 3.0% annual rate in Q2, less than the 3.7% expected, but there are several reasons

But economists said the lower-than-expected number should not be a cause for worry. Sherry Cooper, chief economist with BMO Nesbitt Burns Inc., noted that Q1 growth was revised up to 4.5% as part of the annual benchmark revisions (previously reported as 3.9%), which is a bit of a wash.

In addition, she said, while real consumer spending expanded only 1.0% in Q2 partly due to the spike in gasoline prices, both consumers and business are expected to do better in Q3. Cooper also noted that Friday’s GDP data incorporate complete figures only through May, and as such, the data do not say much about where the economy is now.

Her “bottom line:” This will not affect the Fed’s decision to raise rates Aug.10.”