The Republican-controlled Senate Budget Committee yesterday warned President Reagan that it will wait no longer than today for compromise on defense spending before beginning surgery on his costly military buildup program.

In what amounted to a polite but firm ultimatum, Republican as well as Democratic leaders on the committee said they will make the reductions themselves unless Reagan offers a scaled-down version of his proposal to increase defense spending by 10 percent after accounting for inflation.

There is "no way" the panel will accept a 10 percent boost, said ranking committee Democrat Lawton Chiles (D-Fla.) after an inconclusive meeting with Reagan, the second in as many days that the president has held with committee leaders.

Agreeing with Chiles' assessment, Committee Chairman Pete V. Domenici (R-N.M.) warned Reagan that he will "have to take a chance on what we come up with" if he doesn't propose reductions of his own. The administration has "a choice to do something or they're out of the ball game," added Chiles.

Implicit in the warnings was the suggestion that a go-it-alone budget would require Democratic support--at a price. Hinting at what part of that price might be, Chiles said he told Reagan that he may have to accept tax increases, including some change in the 10 percent individual income tax cut scheduled for July 1, which Reagan has said he is determined to preserve.

"That really ruined his day," said Chiles.

The president, Domenici noted, is "extremely firm" in opposing any tax increases for the next fiscal year. Domenici told the panel he hadn't given up on getting an accord with Reagan on defense, and hinted that there may be an overnight attempt at further negotiations. "I'm an optimist by nature," he observed.

Domenici also rejected what Chiles described as a "rumor" that Reagan didn't care whether Congress passed a budget this year, saying he has seen "nothing to indicate the White House doesn't want a budget resolution."

But if there are no signs of flexibility from the White House beyond the minor cuts that the administration offered earlier this week, which reduced Reagan's after-inflation defense increase proposal to about 9 percent, the committee will "work our will," Domenici said firmly.

It was just such a threat of revolt last year, after committee Republicans joined in a dramatic public rejection of Reagan's own budget and hinted of compromise with the Democrats, that prompted an accommodation with the White House.

That accommodation included reductions in Reagan's proposed defense spending increase for this year as well as tax increases and more social welfare spending than Reagan had initially proposed.

After yesterday's meeting with Reagan, Domenici said Republicans might agree on an after-inflation increase of about 7 percent in order to get roughly 5 percent in conference with the Democratic-controlled House, which has already approved a budget with a substantially smaller defense spending boost. But it was not clear whether a budget with 7 percent for defense could clear the panel, let alone the Senate. Three or four committee Republicans have indicated they support Reagan's full increase for defense, while Chiles said "the vast majority of Democrats are ready to go with 5 percent."