In 2009, first-time buyers accounted for more than 50 percent of sales when recession-era tax credits fueled the real estate market. In the past 30 years, they've averaged 40 percent of sales.

"First-time buyers are important to get the housing market to move to a new plateau," said Steven Ricchiuto, the chief economist for Mizuho Securities USA Inc. "Without them, you just get stuck at a marginal recovery environment."

Overall, sales of existing homes fell 1.2 percent in June to a seasonally adjusted annual rate of 5.08 million, down from 5.14 million in May but up 15.2 percent from June 2012.

The national median price for an existing home was $214,200 in June, up 13.5 percent from a year ago, the association report said.