Continued uncertainty about the extent of future federal budget deficits and the long siege of record interest rates are bound to depress investors and cause continued volatility and some instances of chaos in the nation's financial markets, analysts warned yesterday.

At the same time, investment firm officials interviewed yesterday were virtually unanimous in general support for the current policies of the Reagan administration and Federal Reserve Board. Ultimately, these government programs of spending restraint and tight money will lead to more economic stability, lower interest costs and healthy stock and bond markets, they predicted.

But no one knows when that will happen. "I really see interest rates collapsing and the economy going into what looks like a major recession . . . and the markets will turn around," said economist Sid Wachtel, head of the Wachtel & Co. investment firm here. "But the timing is uncertain . . . three months ago I would have said the same thing," he added.

The only hint of a specific interest-rate forecast yesterday came from investment firm executive George Ferris Jr., who said flatly that congressional elections next fall will force the Republican administration to take some action to guarantee lower rates by July 1.

Indeed, House GOP leader Bob Michel (Ill.) said yesterday that within 90 days, "something's got to give" on interest rates. Otherwise, he said, Congress "may begin to think in terms of credit control," more financial institution regulation or reorganization of the Federal Reserve Board.

Michel's comment was credited with helping bond prices to rise (and interest levels to fall) in a late rally yesterday. Traders said the rally erased Tuesday's losses. The bellwether Treasury issue maturing in 2011, with a 13 7/8 yield, closed up 44/32nds on the day.

The prolonged state of market disarray and high rates has led to some concern about the plight of investors who buy on margin accounts, paying only a certain percent of a stock's price and being forced to liquidate or increase their cash investment as the market declines.

But that problem was described by brokers as limited to a relatively small number of investors who concentrated on specific business sectors where price declines have been greater than in the overall marketplace. A much steeper market decline would have to occur before this becomes a widespread problem, brokers said.

As the markets churned inconclusively yesterday, there was no evidence of panic among investors. But brokers said investors are extremely cautious because they have been burned so much in recent years by ill-fated interest rate and economic predictions. "The people don't really believe" what President Reagan's economic spokesmen are forecasting, said Washington investment firm chief Julia Walsh of Julia Walsh & Sons.

In a seesaw trading session yesterday, the broad Wilshire 5,000 equity index of all publicly traded stocks gained just 0.29 percent. Volume continued to be sluggish, which some brokers interpreted as evidence that the market bottom is yet to come.

As described by John Brooks of the Atlanta firm of Robinson-Humphrey & Co., yesterday's "little rally . . . looks very anemic" compared with a sharp decline in the last month. He said he is pessimistic about the near-term outlook for the market.

Walsh also expressed concern at the absence of any significant rallies during the dramatic stock-market sell off, which she said normally would be expected.

What has happened, several investment executives said, is that many investors expected too quick a fix to economic problems that developed over a long period of time. And the consequences of not being able to change gears rapidly in a complex economy have included a 15-month low for the Dow Jones blue chips as well as record low prices in the bond market.

"When President Reagan was elected, there was a general feeling of confidence . . . and stocks reacted strongly, probably prematurely," said Leslie Silverstone, vice president and manager of Dean Witter Reynolds in Washington. "It's become obvious it will take longer to reverse economic trends and that no matter who is in the White House, there are certain problems" that can't be solved within a specific timetable that many investors desire, he added.

"We don't think recent market activity is a tremendous vote of no confidence in Ronald Reagan," said John Pearce of the E.F. Hutton office in Bethesda. "Investors are a very shaky breed, and if their stocks don't go up, they sell . . . It's short-sighted."

Reagan was closeted with his economic advisers yesterday, and no formal announcement of new defense or other budget cuts is expected before next week. But White House Deputy Press Secretary Larry Speakes sent another message to Wall Street, emphasizing that Reagan expects to maintain a "hard line" on the budget.

The budget deficit for the year starting Oct. 1 will stay at $42.5 billion, and the budget will be balanced by fiscal 1984, Speakes asserted.

Ferris, chairman of Ferris & Co. in Washington, expressed the consensus of his colleagues in calling on the administration to stick with its budget deficit forecast, even if that means cuts in the Pentagon's budget.

"On reassessment, they can say we can do with less defense spending," but Defense Secretary Caspar Weinberger must publicly support any such budget reductions for them to be credible," Ferris stated.

"The American people don't understand that we could have overkill in defense, and this recognition on the part of the administration could well be the start of confidence" that will rekindle investor interests, he added.

Ferris also emphasized his view that the financial markets would be in much worse shape today with old government spending policies and that "we're suffering our lumps earlier rather than later" in a gradual recovery process.

Another general consensus is that bargains can be found in the markets, and leading Wall Street firms are preparing a series of nationwide programs aimed at convincing investors that the new tax laws as well as economic trends promise rewards. Bache Group Inc. will hold seminars here next week, for example.