The Reagan administration has decided against taking any measures to aid troubled savings and loan associations beyond those already in effect or approved, sources said yesterday.

At a Cabinet Council meeting yesterday, five major decisions were made regarding the future of the thrift industry:

* Federal regulators will continue to administer income capital certificates on a case-by-case basis. ICCs are promissory notes issued by the government to prop up the net worth of thrift institutions to statutory levels..

* The administration refused to support so-called mark-to-market accounting, which could push unprofitable thrift institutions into the black without cash infusions. This type of accounting, used in bankruptcy reorganization cases, calculates an institution's assets at current or market value rather than at face value. The difference between face and market value can be used to generate paper profits, offsetting operating losses.

* The Federal Savings and Loan Insurance Corp.'s $750 million line of credit on the Treasury will not be increased. This measure had been urged because of the fear that the insurer of savings and loans could go broke financing the increased number of government-arranged mergers.

* The group gave its consent to a four-tier system of mergers, which would require federal regulators to merge savings and loans with savings and loans within the same state if at all possible. If not, they could be merged with S&Ls across state lines, or commercial banks within the same state, or, finally, commercial banks across state lines.

* It reaffirmed its support for new asset powers for thrift institutions sought by federal regulators and by most of those institutions. These include making commercial loans and adding many other functions now performed by commercial banks.