"It's a neutral tool targeted at too much money supply in the market so it isn't a signal that policy is shifting to tightening," said Zhang Jianhua in comments published by the official Xinhua News Agency.
The PBOC announced plans last Tuesday to raise the commercial bank reserve requirement ratio by 50 basis points on January 18.
A move had been expected, but later in the first half and only after it had shifted up yields on its sterilization paper.
It will lock up an estimated CNY300 billion in liquidity in the banking system.
Senior government officials, including Premier Wen Jiabao, have said frequently in recent weeks that the "appropriately loose" monetary policy stance adopted at the end of 2008 will remain unchanged.
