In a direct challenge to Congress, White House officials said today that President Reagan would use the appropriations process this fall to seek deeper cuts in domestic spending than are contained in the two-week-old congressional budget compromise.

After a 90-minute White House strategy meeting here, presidential spokesman Larry Speakes said "in many cases" Reagan would seek to hold domestic spending to levels contained in a Senate-approved budget resolution earlier this year.

This would be less spending for many domestic programs than was included in the final House-Senate compromise approved Aug. 1.

Speakes said Reagan would examine every bill for "excessive spending." Reagan would seek to hold spending "very close to the line" of the Senate resolution, "which is the only agreement that will be able to produce true deficit reduction," he said.

A senior White House official said that Joseph R. Wright Jr., acting director of the Office of Management and Budget, had been directed in today's meeting to examine pending appropriations bills and reach agreement with key members of Congress on their actual size, setting the stage for possible later vetoes. The official said Reagan would lay out his plans to Senate Republicans at a White House meeting set for Sept. 11.

The official also said the White House was undertaking a legal study on possible recisions of spending already approved by Congress.

The developments today are the strongest signal yet that Reagan is heading for a confrontation with Congress over spending this fall. In past years, Reagan negotiated his differences over spending bills and rarely vetoed them.

The possible "veto strategy" emerged after the White House was told that the recent compromise budget resolution did not reduce the deficit as much as the $277 billion over three years that Congress had predicted.

However, some administration officials have said in recent days that they fear a series of vetoes could be politically risky because such a strategy would antagonize Democrats whose support is needed for Reagan's other major domestic policy priority, overhauling the tax code.

When Congress approved the budget compromise Aug. 1, Reagan said it "marks only a beginning, not an end." He had praised Congress for not including a tax increase, and said the compromise was "consistent" with the philosophy of his own February budget request.

But he promised at the time to seek deeper spending cuts, and administration officials have acknowledged that the resolution dramatically reordered the president's spending priorities.

The budget resolution only sets spending targets; actual spending is set by appropriations bills. Reagan does not sign the congressional budget resolution, but can veto the appropriations bills.

The prospect of Reagan seeking deeper spending cuts than Congress agreed to this month was criticized today by Christopher J. Matthews, a spokesman for House Speaker Thomas P. (Tip) O'Neill Jr. (D-Mass.). He said Reagan appeared to have "broken with Republicans" in Congress again, and was unnecessarily "picking a fight" with Capitol Hill.

"It's sort of a North Korean strategy to gin up a battle when there isn't one," Matthews said, noting that the compromise budget resolution carried the approval of members of both parties in both chambers.

White House officials also talked about selling Reagan's tax plan, trade issues and the upcoming summit with Soviet leader Mikhail Gorbachev during a strategy session here by telephone with aides in Washington.

Reporters and television cameramen were invited to watch the meeting open; the telephone hook-up was beset with technical problems during the closed meeting, officials said.

Chief of staff Donald T. Regan said the planning meeting was undertaken because "we have to plan ahead. You can't just possibly let yourself drift or be at the mercy of others who would set your agenda."

Responding to criticism that Reagan's second term has been foundering, the chief of staff said the president had accomplished more this year than at any time since his 1981 budget and tax victories.

President Reagan was not involved in today's meeting. He read paper work in the morning and planned to walk around his ranch this afternoon.

The White House announced that Vice President Bush and his wife Barbara would visit the vacationing Reagans at the ranch Wednesday.

Also today, national security affairs adviser Robert C. McFarlane said the United States expects an announcement this week from South Africa on reforms there.

He criticized as "bad law" pending sanctions against South Africa in Congress.

He said the expected announcement from South Africa this week would affect Reagan's decision whether to veto the legislation, but "on certain fundamentals, the president's views are quite firm and quite strong. And his view of the veto or signature of that bill won't be altered by, won't be shaken in those convictions."