U.S. single-family home prices rose in July on a year-over-year basis but fell short of expectations, a closely watched survey said on Tuesday.

The S&P/Case Shiller composite index of 20 metropolitan areas gained 6.7 percent in July year over year, shy of expectations for a 7.5 percent rise.

On a seasonally adjusted monthly basis, prices in the 20 cities fell 0.5 percent in July. A Reuters poll of economists had forecast a flat reading.

Non-seasonally adjusted prices rose 0.6 percent in the 20 cities on a monthly basis, disappointing expectations for a 1.1 percent rise.

"The broad-based deceleration in home prices continued in the most recent data," David Blitzer, chairman of the index committee at S&P Dow Jones Indices, said in a statement.

"While the year-over-year figures are trending downward, home prices are still rising month-to-month although at a slower rate than what we are used to seeing over the past couple of years."

A broader measure of national housing market activity that S&P/Case-Shiller is now releasing on a monthly basis rose at a slower pace year over year, coming in at 5.6 percent.

The seasonally adjusted 10-city gauge fell 0.5 percent in July versus a 0.2 percent decline in June, while the non-adjusted 10-city index rose 0.6 percent in July compared to a 1.0 percent rise in June.

Year over year, the 10-city gauge also rose 6.7 percent.