The Caixin/Markit Services Purchasing Managers' Index (PMI) for China declined to 50.2 in December from 51.2 in November, missing expectations for an increase to 52.3.
The index was driven by a subdued client demand.
Recruitment at services continued to rise in December, while backlogs of work were little-changed.
"In light of the setback to services sector growth, the government needs to gradually relax restrictions in the sector. This will release the potential of supply-side reform, improve the economic structure and help with the industrial transformation and upgrading," Dr. He Fan, Chief Economist at Caixin Insight Group, said.