STOCKHOLM, Sweden (AP) _ Swedish price control officials Tuesday attacked the government for suggesting restrictions on Japanese car imports.

The National Price and Cartel Office said in a sharply worded letter that limiting Japanese imports would raise car prices, boost inflation and reduce freedom of choice for Swedish customers.

The attack was in response to proposed restrictions by the Foreign Ministry's trade department, which claims Japanese car makers are redirecting exports to Sweden because of restrictions in other countries. The ministry dismissed the conclusions by the cartel office.

Sweden, home of Volvo and Saab car makers, was one of the last countries in Europe with a free automobile market, the government department said.

Per-Arne Sundbom, head of the cartel office which is politically independent, told two newspapers that the government was ''shouting before the wolf has come'' by claiming the Japanese were swamping the Swedish market.

Foreign Ministry official Lars Stalberg said that following talks in Tokyo in April, Japanese manufacturers were ready to voluntarily limit exports to Sweden for the rest of the year.

''We feel it was an admission by the Japanese companies that they have subjected the Swedish market to too strong pressure and have used the fact that Sweden has the only open market,'' Stalberg said.

He said Japanese manufacturers increased their market share in Sweden from 15 percent in 1986 to 25 percent during the first part of this year. Toyota, Nissan and Mazda are now among the top 10 importers.

Stalberg denied allegations by opposition leader Bengt Westerberg that the Social Democratic government was violating Sweden's traditional support for free trade.

He said the government had ''taken no action ... only discussed a developement which we find disquieting.''

Japanese cars sold well here because they had a reputation for durability and were cheaper. A new Japanese small car cost about the same as a second- hand Swedish model.

Sundbom said decreased competition would raise inflation, which is more than 6 percent and is nearly twice as high as most of Sweden's trading partners.

The Cartel Office said restrictions would not affect the Swedish-made cars as much as imports from West Germany, which go to the same small-car market.

A Volvo spokesman also said the Swedish giant had not suffered from the Japanese expansion and sales last year were up 14 percent.

Volvo sold a record 73,255 last year, twice as many as its nearest competitor, Ford, said official statistics. Saab was the fourth largest seller in Sweden.