The Veterans of Foreign Wars, in what may be the first of many similar efforts by conservative groups, voted yesterday to establish a fund to provide food, medical and other non-military aid to guerrilla groups trying to overthrow the government of Nicaragua.

Without debate, delegates to the VFW's annual convention in New Orleans voted unanimous approval of a resolution sponsored by outgoing national commander-in-chief James Currieo to establish a "Humanitarian/Truth Fund for Nicaraguan 'Freedom Fighters.' "

The fund is to be administered by the American Security Council Foundation, a conservative group based in Boston, Va., that coordinates the National Coalition for Peace Through Strength.

"Very possibly other organizations in the coalition will come on board. We have taken the lead," Currieo said in a telephone interview.

The House of Representatives voted last month to halt the Reagan administration's covert-aid program to Nicaraguan rebel groups, but the Senate is unlikely to concur and the program, estimated at $80 million over the next two years, continues. Currieo said he hopes to raise $1 from each of the VFW's 2 million members but expects to receive $50,000 to $75,000.

John M. Fisher, president of the American Security Council Foundation, said 65 of its member organizations, including the Teamsters union and the Reserve Officers Association, have agreed to a nationwide public relations effort backing President Reagan's policies in Central America.

Fisher said the groups, whose membership totals 10 million, have also approved a statement backing the administration and Nicaraguan rebels. Although the VFW fund plan is an independent project, "hopefully a number of our member groups will try to join with them," Fisher said.

The groups would have the option of endorsing the VFW fund or setting up their own, he said.

Currieo said the VFW will publish an appeal for contributions in the November issue of its magazine "outlining the plight of the freedom fighters who are trying to regain control of their government." Donations will be used to provide food, clothing and medical supplies to the rebels and to bring some of them to the United States for speaking tours, he said.

A White House spokesman said no comment would be made on the VFW action until the text of the resolution can be studied. Privately, however, officials have said the fund is welcome if the veterans do not violate the law that prohibits supplying arms.

Currieo, 49, of Sierra Vista, Ariz., said that, since last March, he has received several National Security Council briefings on Central America and that the fund idea occurred to him as he followed House committee debates in June on whether to cut covert aid.

"I had a strong feeling we were being forced into another retreat," Currieo said. He insisted that no one in the White House had suggested the plan to him.

Last month, Currieo spent a week in El Salvador, Honduras and Costa Rica and met in Honduras with leaders of the rebel groups. "We call them 'freedom fighters' and not 'contras' because that's the term of the Nicaraguans and the Cubans," Currieo said, referring to the truncated version of the Spanish word contrarevolucionarios, or counterrevolutionaries.

"We promised them nothing, but we indicated we would go back and try to focus public attention on their fight," he added.

Currieo returned to brief Reagan on his findings and said he did not tell him then about the planned fund. He said the administration was informed later.