The Senate Foreign Relations Committee began drafting a foreign aid bill yesterday by voting tentatively for a partial spending freeze that would provide $417 million less than the amount requested by President Reagan for the 1986 fiscal year.

However, the committee stressed that its $12.8 billion overall figure, approved without dissent, is intended as a "framework" from which to work as senators consider a number of controversial aid decisions affecting areas such as Central America and the Middle East. As a result, the amount could change by the time the committee reports a bill to the floor.

Yesterday's action, which follows the austerity blueprint laid out by the Senate Budget Committee, meets the administration's request for increasing military and economic aid to Israel to $3 billion and to Egypt to $2.3 billion.

But in all other categories the committee voted to freeze spending at this year's levels or to cut it in some cases.

The administration proposed a fiscal 1986 aid package of $15.9 billion, of which $13.2 billion falls in the jurisdiction of the Foreign Relations Committee.

In fixing the amount at $12.8 billion, the committee followed two approaches. In categories where the administration asked for increases over fiscal 1985 appropriations, the committee froze the amounts at this year's level. In those categories where the administration proposed cuts, the committee took the lower figures.

In regard to Israel and Egypt, the committee stated that its total assumes military aid increases of $400 million and $125 million respectively. That would give Israel fiscal 1986 military aid of $1.8 billion, with its economic aid remaining at the 1985 level of $1.2 billion while the administration and Congress ponder an Israeli request for additional emergency assistance of $1.5 billion over two years.

Egypt's military aid would be boosted to $1.3 billion, while it would continue to receive economic assistance at this year's level of $815 million with $213 million in food aid.

These were the only two countries cited in yesterday's action. The rest of the amount voted by the committee was earmarked for broad categories of economic and military assistance and did not include levels for specific nations.

However, if the committee sticks to its $12.8 billion figure, there will not be enough money for the administration to meet its goal of increasing aid to several other countries, such as Turkey, Morocco and Central American nations, that it considers priority cases.

In order to meet its aid goals for these countries, the administration either would have to ask Congress for more money or, failing that, reprogram available funds by shifting money tentatively earmarked for some countries to others that it considers more important.

Congress has not been able to pass a foreign aid bill for four years, providing assistance instead through "continuing resolutions."

Later in the day, Langhorne A. Motley, assistant secretary of state for inter-American affairs, told the committee that he could find "no kind of overt mechanism that works" to put pressure on the leftist government of Nicaragua to change its politics.

As a result, he said, the administration plans to ask Congress after the Easter recess to give the Central Intelligence Agency $14 million for covert aid to antigovernment rebels in Nicaragua.

Sen. Christopher J. Dodd (D-Conn.) demanded assurances that the administration would not try to channel funds for the rebels through third parties.

"Even if today we wanted to, we couldn't because there's a prohibition," Motley said. "If you want my assurance, I'll give it to you . . . I'm not looking for loopholes. Nobody's going to play games with you or other members of Congress."

Asked later whether the rebels are seeking to overthrow the Nicaraguan government or to change its attitudes, Motley replied: "What may or may not be in the minds of one or more of the 15,000 is a sidebar issue" compared with the issues of U.S. national interest.