The smaller Shenzhen index ended down 0.24% and the start-up board ChiNext Composite index was weaker by 1.055%. Wuhan, the epicentre of the novel coronavirus outbreak in China, reported on Monday five new confirmed cases, all of whom live in the same residential compound.
China reported 17 new COVID-19 cases in the mainland on May 10, marking the highest daily increase since April 28.
The country's central bank on Sunday signalled more policy support for the economy and said it lowered interest rates on its standing lending facility (SLF) in April.
China's central bank said on Sunday it will step up counter-cyclical adjustments to support the economy and make monetary policy more flexible to fend off financial risks.