The IHS Markit Russia Services Business Activity Index dropped to 52.6 in July from 55.5 in June. Economists had expected the index to fall to 55.0.
However, any reading above 50 indicates expansion in the sector.
Among components, new business growth softened to a nine-month low in July. Employment in the sector expanded for the seventh successive month.
On the price front, both input and output price inflation were moderate in the context of the respective series histories despite accelerating.
The degree of optimism in the Russian service sector was the weakest so far this year.
The Composite PMI, which combines manufacturing and services, fell to 53.4 in July from 54.8 in the prior month.
"The Composite Index signaled a softer output expansion in July, due to accelerated growth in the manufacturing sector being outweighed by a slower service sector upturn," Sian Jones, Economist at IHS Markit, said.