Secretary of State George P. Shultz, citing "unprecedented financial difficulties," has withdrawn his invitation to the Organization of American States to hold a foreign ministers' meeting in San Francisco next month, it was disclosed yesterday.

Shultz made known his decision in a letter to OAS Secretary General Joao Clemente Baena Soares.

U.S. officials, insisting on anonymity, said the cost to the Treasury of hosting the meeting in San Francisco would have been $909,000. Instead, the meeting will be held at OAS headquarters here.

Hosting the meeting on the West Coast would have required U.S. taxpayers to foot the bill for hotel and transportation for OAS employes sent to the conference.

The foreign ministers of the 32-nation body meet annually. This year's session is considered especially important because it opens on Nov. 9, two days after the deadline for implementation of the Central America peace agreement.

Budgetary restrictions are forcing the State Department to cut 1,270 jobs, about 8 percent of the total. In addition, two embassies and 13 consulates are being closed. Department budget officials have said they regard the hosting of the OAS meeting in San Francisco to be a luxury under present circumstances.

Other officials expressed embarrassment that the United States withdrew the invitation. They noted that St. Lucia, a tiny Caribbean island with a population under 150,000 and a 1984 gross national product of $148 million, hosted the OAS meeting in 1981.