Rising gasoline and heating oil prices pushed up producer prices for finished goods by 0.3 percent in April, the largest increase since last November, the Labor Department reported yesterday.

Consumer food prices, on the other hand, fell 1 percent, the fourth consecutive monthly decline.

Analysts do not expect petroleum product prices to continue to rise for long, and they are generally sticking with predictions that finished-goods prices charged by producers will go up only about 1 percent or so in 1985.

In the 12 months ended in April, finished-goods prices rose 0.7 percent. The rise in March was 0.2 percent, the department said.

However, the forecasters also expect that inflation will pick up at least modestly over the course of 1985, with finished-goods prices climbing at a 2 to 3 percent rate before the year is out.

Gasoline prices shot up 9.5 percent last month and fuel oil prices rose 10.5 percent, but the price of both commodities remained about 5 percent lower than in April 1984. The increases included in the April finished-goods index actually occurred in March, but the changes regularly are incorporated with a one-month lag because of delays in gathering the information.

The higher prices for petroleum products are the result of tighter supply conditions caused by cutbacks in money-losing refinery runs. Many refineries in the United States have been operating at a loss for some time, industry officials have said.

Spot market prices for gasoline peaked in the first half of April and have softened slightly since. Heating oil prices peaked a few weeks earlier and have come down nearly 10 cents a gallon since then, according to weekly figures through last week published by the Energy Information Administration.

Some occasional periods of tight supplies, particularly for gasoline, could occur with oil industry inventories running at unusually low levels. Nevertheless, most industry analysts do not expect a continued runup in prices because crude oil supplies are so plentiful worldwide that the average price for crude oil being traded has dipped from $28.33 a barrel on Jan. 1 to $27.69 currently, the EIA reported.

The decline in consumer food prices in April left that portion of the producer price index 0.7 percent lower than it was a year ago. The only substantial increases last month were for fish, up 2.5 percent, and eggs, up 6.9 percent. Beef, veal, pork and poultry prices all fell.

Finished-goods prices other than for food and energy fell 0.1 percent after rising 0.5 percent in March. Capital-goods prices were unchanged following a 0.4 percent increase in March and a 0.5 percent increase in February.

Prices for intermediate products rose 0.2 percent after falling by the same amount the month before. Even with the increase, that portion of the index remained 0.3 percent lower than it was a year earlier.

Crude-materials prices dropped 1.2 percent in April, leaving that portion of the index 0.5 percent below its year-earlier level.