President Reagan said Saturday he has "no choice" but to veto the trade bill and urged Congress to begin work anew and forgo forcing businesses to notify workers of imminent plant closings.

In his weekly radio address, Reagan said the bill, received at the White House Friday afternoon, will "move us a step further toward protectionism.""I have no choice but to send this back to Congress," he said.

Reagan has repeatedly vowed to veto the bill - three years in the making - if lawmakers did not remove the provision requiring that companies give workers 60 days notice of plant closings.

"I don't want to leave the impression that the trade bill is completely bad. On the contrary, it contains some good and important measures," he said.

But "arbitrary rules laid down by politicians and enforced by Washington bureaucrats" is not the answer, Reagan said, charging that in some cases, the plant closing provisions of the trade bill would actually force companies to close their doors.

"There are circumstances in which they would actually force a business to shut down," the president said. He contended that once such a notice is given, creditors, suppliers and customers would abandon the company.

"I believe businesses should give workers and communities just as much warning as they can," the president said. "But when big government gets into the middle of something like this . . . what's intended to help everyday working men and women can actually end up hurting them."

Congress and the White House have been at loggerheads over the plant-closing notification; the Democrats have embraced it as an important gesture for American workers, and the administration has labeled it a symbol of unwarranted government interfer-ence in business.

In the Democratic response to the president, House Speaker Jim Wright, D-Texas, pleaded with Reagan to sign the bill and said 60 days "is not too much to ask."

"Top management knows in advance when its service is no longer required and builds golden parachutes worth millions of dollars for its comfort," Wright said. "Can't we give the workers of America at least 60 days to get their lives in order, to get new training, to cushion the blow?"

"America needs this bill," he said.

But Reagan instead urged legislators to start again.

"I urge Congress to schedule prompt action on a second trade bill immediately after it sustains my veto on this one," he said.

Officials said the veto message would probably be sent to Congress next week. Reagan has 10 days in which to act.

Sen. Alan Simpson, R-Wyo, said Saturday he was confident the veto would be sustained and that a second attempt would succeed.

Simpson, in Hot Springs, Va., to address the corporate members of the Business Council, said if the plant closing provisions and others are stripped or modified, "We'll get something on a very important piece of legislation called the trade bill."

Apparently shy of the votes to override a presidential veto, the Democrats are nonetheless hoping the veto will give them a potent issue in the presidential election campaign because the trade gap, which hit a record $171.2 billion last year, has become one of the most serious threats to economic prosperity.

The 1,000-page bill, signed with great fanfare this past week by Wright, requires that the president act against countries that put up unfair trade barriers against American products.

The reform package, generally agreed upon by the two sides, also is designed to crack down on foreign trade abuses.