The purchasing managers' index (PMI) for China's non-manufacturing sector dropped 0.5 percentage points in March from a month earlier to 54.5 percent, data showed on Thursday.
The index tracks activity in a number of sectors, including construction, software, aviation, railway transport and real estate, according to the National Bureau of Statistics and the China Federation of Logistics and Purchasing (CFLP).
A PMI reading above 50 percent indicates expansion, while a reading below 50 percent reflects contraction.
The decline follows a rebound in February, when the index came up from its lowest level in more than a year in January, data showed.
However, CFLP Vice Chairman Cai Jin remains optimistic.
"The March figure shows the non-manufacturing sector is still within a range of moderate and relatively fast growth," Cai said.
He attributed the slight weakness last month mainly to a drop in business in the tourism, transport and catering sectors after high demand during the Spring Festival holiday from Jan. 31 to Feb. 6.
The sub-index for new export orders surged by 3.4 percentage points to 51.7 percent last month.
The index for business outlook rose 1.6 percentage points to 61.5 percent, marking strengthening corporate confidence.
Employment rebounded 0.5 percentage points to 51.4 percent, while charges also rose 0.5 percentage points to 49.5 percent, data showed.