Oil companies need to stop ripping off the U.S. through price fixing, says real estate developer Donald Trump.

The mogul told CNBC that oil companies have long been working together on the price of oil and should pay penalties for their profits.

"I consider myself to be a great capitalist, but I think the oil companies have been ripping off this country and the world for a long time," Trump says.

"I can see doing something against the oil companies. They're making numbers — nobody's ever seen numbers like this. They and OPEC and lots of people together are having a lot of fun."

Trump added that the U.S. real estate market remains in a depression, but lower prices and the weak dollar are a chance for developers to acquire more land.

Manhattan’s commercial and residential real estate markets are still strong, Trump contends.

"Outside of Manhattan, the United States is closed down," Trump says. "I've built up a lot of cash, and what I'm doing is going around and buying things that two or three years ago were absolutely impossible to buy."

Trump says he is buying zoned land right now that he might have to wait five to seven years to sell.

Trump has been focusing his efforts on projects in China, Russia and Dubai, but he still wants to do more deals in the U.S.

He also criticized banks for holding back on new lending even though interest rates have dropped drastically in the past nine months.

"The banks are virtually out of business," Trump says.

"The banks are not loaning money, and no matter how strong you are, no matter how strong your cash position, it doesn't make any difference. It's very, very hard if not impossible to get any money."

Mortgage and construction loans are still hard to get and now come with strict terms, Trump says.

"The banks are pretty much shut down already," he says. "There is no liquidity in real estate business, limits are really low."

In order to do a $100 million deal, developers now have to put up from 30 percent to 50 percent of equity, he says.

Cash is still king, he says.

"Unless you have cash, a lot of cash, you are essentially out of business," Trump says. "You’re shut out of business."

The economy still faces a great amount of uncertainty, and while it is "not cataclysmic," it remains dismal, he says.

"I’ve never seen a time where the economy is so complex and at the same time so scary," he says.

"It’s a very scary economy. This is a very, very scary time in business."

As for November, the next president should avoid raising taxes during a recession, Trump says.

"Raising taxes at this very critical juncture would be a very bad thing for the economy," he says.