Members of the Organization of Petroleum Exporting Countries are negotiating over production increases that would enable them to make up the oil lost to world markets from Iraq and Kuwait but have not yet agreed to do so, the president of Venezuela and other well-informed officials said yesterday.

Denying reports earlier in the week that Venezuela had promised to increase output by 500,000 barrels a day and Saudi Arabia by 2 million, they said no country wants to act unilaterally. They are seeking a formula that would authorize some members to increase output so long as the total did not exceed the 22.5 million-barrel-a-day limit OPEC imposed on itself last month.

Crude oil prices dropped in New York and London this week partly on the basis of reports that Saudi Arabia and Venezuela had made firm commitments. If they do not deliver the 2.5 million barrels a day oil traders are expecting, prices could surge again.

The shutdown of Iraqi and Kuwaiti production has removed about 4.5 million barrels a day from world supplies.

In a "message of solidarity" to other OPEC members published by OPEC's official news agency, Venezuelan President Carlos Andres Perez pledged "the complete adherence of my country to the agreements reached at the last OPEC conference. . . . My government will not take any unilateral or unconsulted decisions regarding production volumes and export prices."

Saudi officials, who have said nothing publicly, gave similar information to U.S. contacts yesterday.

Meanwhile, the first direct impact of the Persian Gulf crisis on fuel supplies in this country apparently will come from Brazil. Petrobras, the state-owned oil company there, is reportedly reducing exports of gasoline to the United States because its crude oil normally comes from Iraq.

Figures compiled by Oil Daily Editor Marshall Thomas show that Brazil sends the United States about 40,000 barrels of gasoline a day, or 1.72 million gallons. That is not much in a nationwide gasoline market of more than 7 million barrels a day, but its loss could cause regional disruptions, especially in New York and New Jersey, analysts said.