Leading Senate Republicans warned President Reagan yesterday that they cannot vote for the full defense buildup he wants and that minor cuts he has suggested will not be enough. But the president stood his ground against any major surgery on his request for 10 percent growth after inflation in military spending.

Senate Majority Leader Howard H. Baker Jr. (R-Tenn.) predicted after a spirited White House session the senators had with Reagan that "one way or the other we'll find our way out of this morass."

While the president said he might accept small savings in his 1984 defense budget because of lower inflation, reduced fuel costs and a less expensive MX missile basing system, he demanded that the Senate panel not retreat any further from his $239 billion Pentagon spending request.

But Senate Budget Committee Chairman Pete V. Domenici (R-N.M.) told Reagan he lacks the votes for a 10 percent boost in military spending. Domenici said after the White House meeting that Republicans on the panel remain seriously split over the issue.

Domenici and Sen. Lawton Chiles of Florida, ranking Budget Committee Democrat, will meet with Reagan again today before the panel begins to write a 1984 budget resolution.

Sources said that Domenici raised the possibility yesterday of a compromise budget package that could include 5 percent real growth in defense spending for five years, which Domenici said would amount to 93 percent of Reagan's overall goal for increasing military spending over that period.

But Reagan did not appear to be in the mood for compromise yesterday, according to those who attended the hour-and-a-half White House session. Sen. William L. Armstrong (R-Colo.) described Reagan as "utterly dead certain of his ground" on defense spending and not prepared to accept less.

"The president is really hanging tight for his 10 percent real growth" in defense spending, said Baker.

Despite Reagan's unyielding approach, Baker and Domenici hinted vaguely at possible accommodation. Baker said he thinks he can produce a budget compromise, although "I don't know how yet, and I don't know what it's going to be and I don't know what the numbers are going to look like."

Reagan yesterday told the senators "it might be possible" to find savings in his defense budget because of lower fuel costs, reduced inflation and the expectation that a commission will shortly recommend a less costly system for deploying the MX missile.

The president stopped short of putting a price tag on these savings, however, White House spokesman Larry Speakes said in a statement. Domenici said he hoped Reagan would provide details today.

He told reporters yesterday that the savings from inflation, fuel costs and the MX might be less than 1 percent of the president's proposed $239 billion Pentagon budget.

Although some White House officials had hoped this gesture toward defense savings would quiet some of the clamor for larger cuts, Domenici and others made it clear yesterday that it was not sufficient.

After the meeting, Domenici said a 10 percent defense boost "would be very difficult" to get out of the budget panel and Reagan "ended up seeing that on the basis of various senators speaking for themselves, and they all did. There is a very big split among the Republicans, so without Republican unanimity you obviously couldn't get 10 percent."

Of the 12 Republicans on the budget panel, only three or four are believed to support Reagan's full request. Others have said they want defense spending increases of about half Reagan's 10 percent proposal.

"If the committee voted today, we would probably vote and vote and we wouldn't get the 12 members that are needed," Domenici said. "We couldn't get a consensus today."

Later, asked whether Reagan had demonstrated any of the "flexibility" he has been hinting at in recent weeks, Domenici said, "I don't think the president has shown any flexibility to this point."

The House voted a 4 percent increase above inflation in military spending, but the Congressional Budget Office has re-estimated it at less than 3 percent. Domenici said there is agreement among the Republicans on his panel that this level is too low.

Domenici has stressed the importance of reducing huge looming deficits to ease the way for economic recovery. Also, Speakes said in the statement yesterday that Reagan "emphasized on several occasions in the meeting how important it is to pass a budget that not only encouraged economic recovery but also meets the nation's basic security needs."

Despite the apparent standoff at the White House session Baker was reported optimistic that he can put together a compromise. "That is the heart of my stock in trade," Baker told reporters.