WASHINGTON (AP) _ President Reagan said Monday it's time to stop ''hemming and hawing'' about trade problems between the United States and Japan and warned he has not ruled out imposing additional sanctions against Tokyo to resolve trade disputes.

While saying he hopes to be able to lift sanctions against Japan soon, Reagan said, ''we will do what is necessary to see that other nations live up to their obligations and trading agreements with us.''

Reagan's remarks, in a speech before the annual meeting of the U.S. Chamber of Commerce, set the stage for the opening of debate Tuesday in the House on a sweeping trade bill, and meetings at the White House on Thursday and Friday with Japanese Prime Minister Yasuhiro Nakasone.

''The final answer to the trade problems between America and Japan is not more hemming and hawing, not more trade sanctions, not more voluntary restraint agreements - though these may be needed as steps along the way - and certainly not more unfulfilled agreements,'' Reagan said.

''The answer is genuinely fair and open markets on both sides of the Pacific,'' he said. ''And the sooner, the better.''

Reagan said areas in which Japan's markets are more restricted than the United States' include semiconductors, supercomputers, auto parts, telecommunications, construction projects and agricultural products.

Momentum for passage of a trade bill has been fueled by America's huge trade deficit, which hit a record $166.3 billion last year, including a $58.6 billion imbalance in Japan's favor.

An amendment sponsored by Rep. Richard A. Gephardt, D-Mo., would force countries with large trade surpluses with the United States as a result of unfair practices to reduce the imbalances by 10 percent a year or face retaliatory measures such as tariffs and import fees.

On Capitol Hill, House Speaker Jim Wright, D-Texas, supporting the Gephardt amendment, accused Reagan of ''engaging in flights of rhetorical exaggeration'' on the trade issue.

Wright said Reagan and Nakasone knew months ago that the House would be voting on the trade bill this week, and Nakasone ''deliberately chose to come during this week.'' A final House vote on the trade bill is expected Thursday.

Gephardt said the vote on his proposal, expected on Wednesday on the second day of floor debate on the trade bill, ''will be close.'' After testifying before the House Rules Committee, which was considering ground rules for the trade debate, Gephardt told reporters: ''We have to fight for every vote.''

Gephardt told the panel his measure would ''add teeth and accountability'' to U.S. trade laws. ''It is our stick in the closet.'' Gephardt's amendment was criticized as too restrictive by Rep. Dan Rostenkowski, D-Ill. But Rep. Claude Pepper, D-Fla., chairman of the rules panel, called it ''a compromise between doing nothing and protectionism.''

House Republicans, meanwhile, came up with their own proposed trade bill, which would meet some White House objections, and condemned the Gephardt provision, which House GOP leader Robert H. Michel of Illinois called ''a time bomb (that) will blow up in our face.''

Reagan said current laws provide a full range of remedies that fit many different situations. ''That's why some trade legislation now before Congress is dangerous,'' he said.

Reagan said the House bill would ''make us use a steamroller against unfair practices every time, no matter whether the steamroller would open the trade doors or flatten the entire house.''

He singled out the Gephardt amendment as ''a particularly bad proposal'' and said, ''It's better policy to allow for presidents - me or my successors - to have options for dealing with trade problems.

''It's more effective, and we won't risk sending our economic relationship with a friendly country crashing into the sea because Congress put our policy on automatic pilot,'' the president added.

Reagan said that in his talks with Nakasone, he will talk about the trade problems within the context of ''a common dedication to freedom and democracy, broad economic relations and a sharing of defense burdens.''

The key issue on the agenda will be the $300 million in tariffs Reagan imposed against Japanese products in retaliation for Tokyo's alleged violation of an agreement not to sell semiconductor chips at unfairly low prices.

Nakasone said in Japan he would ask Reagan to lift the sanctions, and the president, in his speech, said, ''I hope that, before long, we can lift these and that this episode will be recorded as a small incident in the building of our relationship.''

Presidential spokesman Marlin Fitzwater said there were no signs that Nakasone is bringing information with him that will lead to the lifting of the tariffs.

''We're not aware of any new, specific initiatives that might dramatically change the situation,'' he said. ''That doesn't say they won't happen, but we're not aware of them in advance.''

Fitzwater also said there is no timetable or deadline for lifting the sanctions.

''The sanctions' removal is based upon analysis and examination of the data,'' Fitzwater said. ''We obviously would like to do that as rapidly as possible and to lift the sanctions as soon as possible but there are no commitments to any timetable.

In another development Monday, the Supreme Court killed a lawsuit by American businesses that charged Japanese electronics manufacturers with illegally ''dumping'' television sets and other products in the United States at artificially low prices.

The court, without comment, refused to revive a suit filed by Zenith and National Union Electric Corp., formerly known as Emerson Radio Co.