Jim Cramer blamed "too much optimism" for the market's sharp downturn on his "Real Money" radio show Friday.

"There are so many optimists that we ran out of bulls to buy," Cramer said, referring to the "Investors Intelligence" survey, which has been overwhelmingly bullish as of late. Strong bullish sentiment is often viewed as a contrary indicator foretelling weakness.

When people are too bullish, it takes a lot to move stocks higher, Cramer noted.

For example, in the transports, Federal Express ( FDX) reported earnings Thursday that were a "little off kilter" and the stock sold off. But UPS ( UPS) and Yellow Roadway ( YELL) quickly came out and said they were sticking with previous estimates. Due to the market's psychology, Cramer said, they rose only modestly.

Likewise, instead of focusing on good news about having a pair of bidders for Unocal ( UCL), Cramer said Chevron ( CVX - Get Report) fell because people mistakenly thought China was running out of oil.

Cramer advises traders to use the calm to raise cash because "ultimately the wall of worry will be rebuilt." In the meantime, Cramer says the time is right to buy boring secular growth stocks like Altria ( MO - Get Report) and P&G ( PG - Get Report) instead of names like FedEx. "Play defense."

As for Chevron, Cramer says he likes the oils but has been pruning larger ones in favor of small- and medium-sized gas companies. So he would sell Chevron and, for that matter, Unocal too.

In terms of individual stocks, during the lightning round, Cramer says he is "dubious about the short-term prospects of Hewlett Packard ( HPQ - Get Report). But he would buy computer animation giant Pixar ( PIXR) because sooner or later it will strike that elusive deal with Robert Iger and Disney ( DIS).

On business software player Tibco ( TIBX), Cramer says he would not be too quick to sell the company's stock, despite its recent rough news, on account of Tibco's "unbelievable balance" sheet. Cramer describes the tech company as "a dollar-down-and-three-up proposition, that's probably worth playing."

With regard to Guidant ( GDT), another company that's been in the news for the wrong reasons lately, Cramer told a caller not to buy it as an entry into Johnson & Johnson ( JNJ - Get Report). Instead, Cramer says to just buy J&J shares directly since they have come down nicely and sport a nice dividend yield.

He also told callers to "ring the register" on Legg Mason ( LM - Get Report) after it announced its deal with Citigroup ( C) to swap its brokerage operations for Citi's asset management side.

And on a day when high oil prices helped sink the market Cramer says he would continue buying UnitedHelath Group ( UNH - Get Report) and Halliburton ( HAL - Get Report), a pair of companies that "do well when things are bad and oil is on the rise."

At the time of publication, Cramer was long Halliburton, Altria and UnitedHealth.

James J. Cramer is a director and co-founder of TheStreet.com. He contributes daily market commentary for TheStreet.com's sites and serves as an adviser to the company's CEO. Outside contributing columnists for TheStreet.com and RealMoney.com, including Cramer, may, from time to time, write about stocks in which they have a position. In such cases, appropriate disclosure is made. To see his personal portfolio and find out what trades Cramer will make before he makes them, sign up for Action Alerts PLUS. While he cannot provide personalized investment advice or recommendations, he invites you to send comments on his column by clicking here. Listen to Cramer's RealMoney Radio show on your computer; just click here. Watch Cramer on "Mad Money" at 6 p.m. ET weeknights on CNBC. Click here to order Cramer's latest book, "Real Money: Sane Investing in an Insane World," click here to get his second book, "You Got Screwed!" and click here to order Cramer's autobiography, "Confessions of a Street Addict."