President Reagan ran into opposition from some Senate Republicans yesterday in his attempt to put off action on tax increases and big cuts in basic benefit or entitlement programs until next year.

Sources said some senators were also angry at what they perceived as an attempt by Reagan to blame Congress for delays and excesses in passing money bills that conflict with his budget targets. "If the honeymoon wasn't over before, it's over now," said one well-placed Republican source.

Within minutes after Reagan sanctioned the delay on tax increases and entitlement cuts during a televised press conference, Senate Majority Leader Howard H. Baker Jr. (R-Tenn.) attempted to close Senate GOP ranks behind the decision by issuing a statement hailing it, even though it conflicted with a Senate Republican plan advanced just a day before during a meeting with top White House aides.

"While a different result might have been desirable earlier in the year, I think this was the best and most practical result at this time," said Baker, contending it would be a "mistake for the president to foreclose any of his options" now before he prepares his January budget message.

But a couple of hours later Republicans on the Senate Budget Committee failed to unite behind a strategy outlined earlier by Committee Chairman Pete V. Domenici (R-N.M.) to pass a "pro-forma" budget resolution for 1982 that would in effect put off the hard decisions until next year, as Reagan apparently wants.

"There's far from any agreement that we should go ahead with a pro-forma resolution, or a wait-until-next-year kind of budget resolution," said Domenici after the session.

Domenici had led the fight to begin moving this year toward tax increases and entitlement cuts but, shortly after Reagan's press conference, indicated that he, like Baker, was willing to go along with delay. "I'm disappointed but I also don't think we could do it if the president isn't comfortable with it," said Domenici.

It was thus unclear last night whether Domenici and other Republicans on the committee would part company with Reagan and push ahead for action this year on tax and entitlements. Domenici declined to speculate but said more meetings are likely before any decisions are made.

Meanwhile, Reagan's renewed threat during the press conference to veto money bills that exceed his budget targets focuses attention on the stop-gap "continuing resolution" that Congress must pass by Nov. 20 to keep the government running, and initial signals from Congress on that score were not encouraging to the White House.

A resolution prepared for consideration by the House Appropriations Committee tomorrow calls for spending levels well above targets set by Reagan in his September budget proposals, making it a target for a possible presidential veto.

Asked whether Reagan might veto a continuing resolution that exceeds his target, Baker told reporters that such an option was discussed by White House aides in their meeting with Republican senators Monday. But he added, "I think we'll have a bill he'd Reagan can sign." Others indicated less optimism, saying a showdown over the resolution now appears likely.

The entire government is operating under a continuing resolution now because there has been no final action on any appropriations bills for the executive branch. The current resolution expires Nov. 20, necessitating renewal by then to keep money flowing into government departments and agencies.

Failure to meet the deadline with a bill acceptable to Reagan would, theoretically at least, mean a shut down of the entire government, except for national security and other vital activities.

Under the House draft, the next resolution would last until the end of the fiscal year on Sept. 30, 1982. Lower spending levels would take effect only as appropriations bills are passed. But all of them so far also exceed Reagan's latest spending targets, even those passed by the Republican-controlled Senate.

The Senate Republican plan, which Reagan implicitly rejected yesterday, called for $163 billion in tax increases as well as spending cuts over the next three years, starting with action this year to put them in place.