The economy isn't strong enough to stand on its own two feet, and the assistance provided by the Federal Reserve is beginning to create bubbles, says New York University economist Nouriel Roubini.

At a breakfast event Friday, Roubini cited "frothiness" in housing, junk bonds and potentially bitcoins, according to Fortune. The situation could play out into a financial crisis in the next two to three years, Roubini says.

He sees economic growth accelerating this year, but not enough to boost the wages of average Americans. That, in turn, will starve the economy of the consumer spending and debt reduction it needs to thrive, Roubini explained.

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U.S. GDP growth averaged an annualized 2.6 percent during the first three quarters of 2013.

"The question is whether we have gotten to sustainable growth that is not based on bubbles," Roubini said. "Not yet."

As for stocks, he believes earnings growth is decelerating, stating that equities aren't in a bubble now, but they are expensive.

Not everyone agrees. University of Pennsylvania finance professor Jeremy Siegel sees the Dow Jones Industrial Average heading for 18,000 to 18,500.

"I still think we are below fair market value, so I still think we've got 10 to 15 percent to get there in the markets," he told CNBC.

The Dow closed at 16,458.56 Friday.

Meanwhile, Roubini doesn't believe the energy boom in the United States will have as great of an impact in the price of oil as many believe. Since many countries in the Middle East are dependent on oil revenue, lower revenue could lead to instability in the area, which usually results in higher oil prices.

In addition, Roubini said the United States is underinvesting in infrastructure and education, which will worsen the income inequality problem.

"Capital will do well, and skilled labor will do well," he noted. "Blue collar workers, not as much."

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