SHANGHAI — China’s central bank used a longer-dated tool to inject cash into the financial system for the first time in seven months, intensifying its effort to cool a domestic bond market that has thrived on an influx of cheap, short-term money.

The move also signals that the People’s Bank of China prefers using such flexible money market instruments to adjust the supply of funds and shows it isn’t in a rush to use more powerful easing weapons like cuts in interest rates or banks’ reserve requirements.