Senate Finance Committee Chairman Bob Dole (R-Kan.) and other committee members told U.S. Trade Representative William E. Brock in a private meeting yesterday that all trade negotiations and discussions are within his jurisdiction and that they are unhappy with reported attempts by the State Department to move in on trade functions, congressional and administration sources said.

The 90-minute meeting, called by Dole, consisted of informal discussions on outstanding trade issues and negotiations, including imports of Japanese-made cars, the sources said.

Last week on the Senate floor, Dole said he was concerned about who was handling trade matters. Secretary of State Alexander M. Haig Jr. reportedly wanted to take the lead in the Japanese auto discussions to the surprise of both the Japanese and Brock.

The administration is preparing an interagency group of government officials to meet with the Japanese -- probably next week -- for discussions, not negotiations. Delegates from the U.S. Trade Representative's Office and the Departments of State, Commerce and Transportation will participate, sources said.

Following reports in The Washington Post last week of Haig's attempts, Brock was reassured by President Reagan that he would have the lead in any trade discussions, a USTR spokesman said last week.

The meeting yesterday was organized by Dole to "rally around" Brock, one source said.

Meanwhile, the administration reportedly is preparing to announce late this week its plans to help the auto industry, sources said. It wants to tell the public what it plans to do to help Detroit before it discusses it with the Japanese, sources said.

The administration is expected to say it wants to signal to the Japanese to restrict their automobile exports to the United States voluntarily, and it will modify safety and environmental regulations to help the auto industry.

Also at the meeting, Sens. John C. Danforth (R-Mo.) and Lloyd Bentsen (D-Texas) said they were determined to press forward with their legislation to limit imports of Japanese autos to 1.6 million cars a year for three years. Last year 1.9 million Japanese cars were sold here.

There was also agreement that the Senate had enough votes to pass the legislation, sources said. On Tuesday Danforth had asked Dole to speed up debate on the legislation just in case discussions between Japan and the United States leave the import question unresolved.

Also present at the meeting were Sens. Russell B. Long (D-La)., William V. Roth (R-Del.), John H. Chaffee (R-R.I.), Bill Bradley (D-N.J.), John Heinz (R-Pa.), Spark Matsunaga (D-Hawaii), Max Baucus (D-Mont.) and Rudy Boschwitz (R-Minn.), the sources said.