Reagan administration appointees endorsed further deregulation of the trucking industry yesterday despite the fact that the White House has legislation to do so "on hold."

Transportation Secretary Elizabeth Hanford Dole, Interstate Commerce Commission Chairman Reese H. Taylor Jr. and William F. Baxter, chief of the Justice Department's Antitrust Division, told the Senate Commerce Committee that they favor eliminating most remaining regulatory requirements.

The Motor Carrier Act of 1980 removed most of the rules for trucking companies seeking to begin service, add new routes or change freight rates, but they still enjoy antitrust immunity to set some types of rates and have to file voluminous reports with the ICC.

The DOT and the ICC have drafted legislation to eliminate those features. The Office of Management and Budget reportedly has endorsed that legislation. But it remains "on hold" at the White House, and it is widely supposed that one reason is that the Teamsters union opposes further deregulation and the Reagan White House covets further Teamsters political support.

"It's a matter of timing when we go to that next step," Dole told Sen. Bob Packwood (R-Ore.), the committee chairman. "As the economy picks up . . . attitudes will change to broaden support for further deregulation."

Taylor, widely perceived as pro-regulation when he was appointed, has urged the White House to speed deregulation. He amused a roomful of trucking lobbyists yesterday when he said, "On any kind of a cost-benefit analysis, what we are doing now is ridiculous. It is regulation for regulation's sake. It is monumental paper-shuffling. It is absolute nonsense."

Packwood strongly backs deregulation and proposed yesterday to trade a phase-out of the ICC over several years for continued antitrust immunity if that would build a sufficient consensus.

Jackie Presser, president of the Teamsters, was scheduled to testify but withdrew, according to committee sources, because of the five-minute limit the committee placed on opening statements. In prepared remarks, read by another union official, Presser said deregulation "has had disastrous consequences for our members."

Dole said the recession is largely to blame for dislocations in the trucking industry and that shippers, even in rural communities, are being well served.