The regulation of the money supply through various tools of government action

The regulation of the money supply through various tools of government action is called a monetary policy. 

A monetary policy is the process by which the monetary authority of a country, usually the central bank, controls either the cost of very short-term borrowing or the monetary base, often targeting an inflation rate or interest rate to ensure price stability and general trust in the currency. It is also associated with the interest rates and availability of credit.