Leaders among the nation's governors reacted warily yesterday to the proposals under study by the Reagan administration to increase federal gasoline and excise taxes and turn a share of the proceeds over to the states.

The governors say they fear that the contemplated federal tax increases on tobacco, alcohol and cigarettes would preempt revenue sources they regard as their own.

"These taxes have long been regarded as state revenue sources, and should remain so," Gov. Richard A. Snelling of Vermont, president of the National Governors' Association, said in a letter to President Reagan last week.

"The governors share your desire to return revenue sources to the states, not to remove them," Snelling wrote. "It is hard to see what federalism objectives are to be served by federal increases in taxes which any state can, if it wishes, increase to meet its own needs."

The increases in federal excise and gasoline taxes are reportedly part of a complex series of tax and program swaps the president is contemplating between the federal government and states and cities. He is said to be preparing to announce these in his State of the Union Message next week.

Sources indicated that well over half the money raised from those taxes would be used to reduce the federal deficit, with the rest going to states. In return, states would take over some federal education programs.

William Clohan, undersecretary of education, said in an interview yesterday that the administration is considering shifting to the states "more than $1 billion" in education programs while retaining the $3 billion Title I program for poor children at the federal level.

The package also was reported to include a tradeoff of welfare programs, with the federal government taking over the estimated $4.5 billion state share of Medicaid payments for the elderly and state portions of Supplemental Security Income (SSI) payments for the elderly and disabled, in return for a state assumption of the federal share of Aid to Families with Dependent Children (AFDC).

Sources close to the governors indicated that they were particularly concerned that if the administration raises excise taxes Congress might decide to use most of it to reduce the deficit, leaving the governors without a taxing source or much of any new money.

Transportation Secretary Drew Lewis reportedly told state and local organizations earlier this week of an administration plan to raise the federal tax on gasoline by 4 cents and use the money for highway construction.

He told them there are proposals for raising the tax on highway users by 1 cent, with the proceeds going to cities to help meet capital costs of mass transit systems.

Several governors, including Virginia's Charles Robb and Maryland's Harry Hughes, have announced plans for raising gasoline taxes. The source close to the governors indicated that most governors prefer raising this tax themselves, since they could be assured of receiving the money to pave roads and fill potholes in time for this fall's elections.