Apple could face production problems just as the peak festive shopping season looms.
Several key suppliers have suspended output at Chinese factories for some days.
They say it's to comply with tighter energy consumption policies imposed in the country.
China is also grappling with tight coal supplies, which have triggered a contraction in industrial production in several regions.
Apple supplier Unimicron Technology said late Sunday (September 26) that three of its China susbidiaries had stopped production.
It said that was to comply with "local governments' electricity limiting policy".
Concraft Holding, which makes speaker parts for iPhones, said it had stopped output for five days.
Reuters sources say Foxconn, which makes many of Apple's handsets, had to adjust production at one plant.
The stoppages were also hitting suppliers to Elon Musk's electric car brand Tesla.
It's already been grappling with the global shortage of computer chips.
However, major Taiwanese chipmakers TSMC and UMC said their China facilities were still operating for now.