The Pending Home Sales Index, based on contracts signed in the month, rose 0.1 percent to 90.7. The index is 6.7 percent higher compared to the same month a year ago, NAR said.

"Rises in contract activity show buyers are becoming more active even as they face much more stringent loan underwriting standards. Speedy clarification of the appraisal rules could smooth a housing market recovery and support the overall economy," NAR chief economist Lawrence Yun said in a statement.

The index rose highest in the Northeast, jumping 3.1 percent to 80.9. In the West, the index rose 2.2 percent to 96.9. In the Midwest, the index fell 1.3 percent to 89.2. In the South, it fell 1.7 percent to 92.6.

The affordability index fell to 171.6, off its April record of 178.8. In the month, the median price for existing single-family homes was $172,900, NAR said.