Saudi Arabian Monetary Agency (SAMA) said local market indicators were good.
Saudi Arabia's central bank said it would deposit about 20 billion riyals ($5.3 billion) at commercial banks and introduce two new money market instruments to fight a surge in market interest rates caused by low oil prices.
It will inject the funds in the form of time deposits on behalf of government entities to "support financial stability", it said on Sunday, without naming the entities or providing other details.
It will also introduce seven- and 28-day repurchase agreements to lend money to banks when needed. Previously, the central bank has typically only used repo agreements with one-day maturities.
Low global oil prices have slashed government revenue and the volume of petrodollars flowing into the Saudi banking system. Total deposits at commercial banks, which grew continuously for years, were down 3.3 percent in June from a year earlier.
This has strained liquidity in the banking system and pushed up interbank money rates. The one-year Saudi interbank offered rate has jumped by more than 1.5 percentage points in the past 15 months.
That in turn threatens banks' ability to lend to the private sector at affordable rates, a key consideration as the government tries to limit damage to the economy from cheap oil, and raises borrowing costs for the government, which is selling bonds to the banks every month to finance a big budget deficit.
The central bank has been battling to slow the rise in money rates since early this year, cutting back its sales of bills to banks.
Since the second quarter it has been making special provisions of longer-term funds to banks that need them through deposits or low-interest loans, banking sources told Reuters, but it has kept its operations largely secret.
Sunday's announcement appears to be an effort to make its money market management more transparent and predictable, which could ease investors' concerns.
Upward pressure on Saudi money rates could increase late this year if, as some economists expect, the United States resumes tightening monetary policy.
Some bankers think the Saudi central bank will ultimately decide to take stronger steps to restrain rates, such as raising the ratio of deposits which commercial banks are permitted to lend out and reducing the amount of reserves which they must deposit with the central bank.
In its statement on Sunday, the central bank reiterated that the Saudi banking system was still healthy, with non-performing loans totalling no more than 1.3 percent of all loans and provisions set aside for bad loans at high levels.