OTTAWA, Sept 15 (Reuters) - Canadian home sales fell 0.5% in August from July, though the average selling price rose on a month-over-month basis for the first time since March, data from the Canadian Real Estate Association showed on Wednesday. The national average selling price was C$663,503 ($523,556) in August, up 0.3% from July and jumping 13.3% from a year earlier, the industry group said. Actual sales, not seasonally adjusted, fell 14% from a year earlier, while CREA’s Home Price Index was up 21.3% on the year and up 0.9% from July. ($1 = 1.2673 Canadian dollars) (Reporting by Julie Gordon in Ottawa)