US President George W Bush has told worried Americans it will take time for the Wall Street bailout bill to take effect and for confidence to return to the financial markets.

Speaking as worldwide stocks went into freefall, Mr Bush said he was certain the $US700 billion ($A913.0 billion) package that cleared Congress on Friday will work.

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"I believe this plan will work over time," he said, speaking in the midwestern city of Cincinnati.

"In the long run the economy is going to be fine. It is a resilient economy, a productive economy," he said.

Recounting a meeting with small business owners in San Antonio, Texas, he said those he had spoken to "were rightly concerned about our economy and their ability to get credit". 

Mr Bush said, "I told them to keep selling your products and working hard".

Restoring confidence

"It's going to take a while to get in place a program that, one, is effective and, two, doesn't waste taxpayers' money," he told them. "We don't want to rush into this situation and not have the program be effective.

"It's going to take a while to restore confidence in the financial system - but one thing people can be certain of is that the bill I signed is a big step toward solving this problem."

The president told reporters his chat with the proprietors of a San Antonio car dealership, an auto repair shop and two restaurants had been "very illuminating".

"It's clear they're dealing with the effects of a credit crunch," he said. "They're having trouble getting money to be able to continue to expand their business or money to help their consumers be able to buy their products."

And he acknowledged the concerns of many Americans, who believe their tax dollars are being hijacked to bail out profligate Wall Street money barons.

"A lot of the people here in Texas and around the country aren't pleased with the government having to take the steps they took," he said.

'It won't happen again'

"Their question is, 'I pay my bills, I pay my mortgage, why are you helping Wall Street?'

 "The answer is because, had we not done anything, people like the folks behind me would be a lot worse off," he said, referring to the local entrepreneurs.

"We'll make sure that as time goes on, this doesn't happen again. In the meantime, we've got to solve the problem."

The president "will stay very engaged on what's going on on the economic front," said White House spokesman Scott Stanzel, noting that he is scheduled to talk with business leaders in Virginia on Tuesday.

"Obviously, we watch very closely the economic situation not only in this country, but around the world.

"And the officials from Treasury, Federal Reserve, FDIC, and other agencies throughout our government are in regular contact with their counterparts overseas to work cooperatively to promote stability and confidence in our markets," Mr Stanzel said.