President Reagan intends to make a major speech that would define his foreign policy goals but is postponing it until Congress acts on his plan to cut income taxes, White House sources said yesterday.

Despite a sense in and out of the administration that it would be useful for Reagan to spell out his foreign policy more than he has so far, the president has decided that to do so now would divert attention from his tax plan.

"We kept our eye on the budget cuts and got them," said one source close to the president. "Now we intend to do the same with the tax plan."

Another high administration official acknowledged that there was some confusion created by Reagan's unexplained statement in a commencement speech at Notre Dame when he said, "The West won't complain communism, it will transcend communism."

This official said he interpreted the remark as a reference to the ultimate fate of the communist system and said that it would be necessary to "contain" the Soviets in the meantime.

Whatever Reagan meant, it is remarks such as these that have caused some concern in the White House that the president has failed to spell out his foriegn policy aims beyond taking a noticeably tougher anti-Soviet stand than his immediate predecessors. And there have been criticisms, even from quarters friendly to the president, that the administration has reacted to foreign policy questions on an issue-by-issue basis rather than defining its larger goals.

One White House official said yesterday, even while acknowledging some merit to thse criticisms, that it was more important in the long run for Reagan to achieve his economic goals.

Another official pointed out that the Reagan plan, if successful in reducing inflation and stimulating investment, would have "positive foreign policy consequences" because allies would be encouraged by a turnaround in U.S. economic conditions.

Reagan's problems in defining foreign policy issues have been compounded by a change in his speechwriting operation. Chief speechwriter Ken Khachigian, a veteran of the Nixon speechwriting team, returned to California in April and his post has not been filed. Some speechwriters have left the White House, and Anthony Dolan appears to be gradually working into the Khachigan job.

In the past, Reagan has usually needed a long acquaintance with a speechwriter before he begins to feel comfortable with the material that is provided him. There are those in the White House who say that the uncertainty in the speechwriting team has contributed to be confusion over foreign policy.

But the overriding consideration, White House sources emphasized, was that a decision has been made by Reagan in consultation with chief of staff James A. Baker III and counselor Edwin Meese III to concentrate on his tax plan to the exclusion of other issues until it is passed.

"The economic program is at the heart of what Reagan has proposed," said one official. "We're not going to be diverted.