Radio stations in a number of cities are urging motorists to refuse to purchase gasoline Thursday to protest rising prices since the Iraqi invasion of Kuwait.

KHYS-FM in Houston began asking motorists today to purchase gas any day this week except Thursday and to show support for the protest by driving with their headlights on.

Sheldon Hicks of WPGC-FM in Greenbelt said the gasoline protest is ''to show solidarity, that we {Americans} won't be pushed around.''

''We had about 50 calls from people {supporting the protest} this morning,'' said Steve Hegwood, KHYS program director. ''I'm sure that by Thursday, we'll probably have 3,000 or 4,000 people supporting it.''

Radio stations in New Orleans, Los Angeles and Riverside, Calif., Charlotte, N.C., Orlando, Mobile, Ala., and Greensboro, Ky., also are supporting the protest, Hegwood said.

''This has become more than an economic issue,'' he said. ''People rely on their vehicles too much here in Houston. A car is a necessity, and for the oil companies to hike gas prices without proper justification is ridiculous.''

John Rockweiler, general manager of WQUE-FM in New Orleans, said his station will urge people to avoid the pumps Thursday and to drive with headlights on as a show of support.

''The poor everyday person usually doesn't get an opportunity to make statements to say how upset they are,'' Rockweiler said. ''You don't have to be a Saddam Hussein or a George Bush even to make your point. You can be the everyday citizen and probably be more powerful by avoiding the pumps.''

The Automobile Association of America said a spot check Monday showed the average price for self-serve unleaded gasoline was $1.216 a gallon, down 3.4 cents since Aug. 10 and a total of 3.7 cents since Aug. 9, when prices first showed signs of easing.

Despite the moderating trend, gas prices across the country were up 13.6 cents a gallon since Iraqi aggression prompted a crisis in the Middle East that has pushed crude oil prices higher all over the world.

The comprehensive Lundberg Survey, which polls 13,000 gas stations nationwide, said gas prices as of Aug. 12 were up an average of 10.2 cents a gallon for all grades of gas since July 20.

''A lot of our attention is focused on the situation in the Middle East,'' Hegwood said. ''A lot of our worries are to the thousands of American soldiers on foreign soil. The oil companies have taken advantage of the situation and found a reason to increase gas prices. We, as consumers, have to take a stand.''