Sales of single-family homes, town homes, condominiums and co-ops declined to an annual rate of 4.86 million units in the month, the association said.

In May, the annual rate was 4.99 million units. A year ago in June the annual sales rate was 5.75 million units, the report said.

Total inventory of homes on the market would take 11.1 months to sell at current prices, an increase over May's supply schedule of 10.8 months, the report said.

A recent study showed that "nearly a quarter of potential home buyers are waiting on the sidelines," NAR President Richard Gaylord said.

NAR Chief Economist Lawrence Yun said may of the sidelined buyers are potential first-time buyers. "About four in 10 homes are purchased by first-time buyers, which frees existing owners to trade up," Yun said.

At $215,100, the national median price for existing homes sold declined 6.1 percent in June from a year ago, the report said.