A trader speaks with a stock market official beneath the electronic board at the Tehran Stock Exchange, Sept. 15, 2010. Caren Firouz | Reuters

Nothing is easy for Iran's economy these days, and things could soon get even tougher. The U.S. House of Representatives is expected to pass a bill Tuesday to put new sanctions on Russia, North Korea — and Iran. A Senate version passed overwhelmingly last month. Iran is being targeted for its activities in Syria, its ballistic missile program and other "destabilizing activities," according to the Senate's version of the legislation. Under the terms of the 2015 Iran Nuclear Deal, Tehran is not immune to new sanctions as punishment for activities outside of the country's nuclear program.

Men use their smartphones to follow election news as posters of Iran's President Hassan Rouhani are seen in Tehran, Iran May 17, 2017. TIMA | Reuters

Ramin Rabii, CEO of Turquoise Partners, Tehran's largest investment firm for foreign money, said "there is definitely some worry over new sanctions, especially of their impact on business with Europe and Asia." There are bright spots, however, for the Iranian economy: "One of President (Hassan) Rouhani's greatest achievements," said Rabii, "has been to lower inflation from 45 percent down to a much more manageable 10 percent."

The next big economic problem?

But that moderating inflation has caused another problem to surface. Lower inflation combined with soaring interest rates — sometimes as high as 25 percent — have the country's top banking officials warning of a potential crisis. During the presidency of Mahmoud Ahmadinejad, many banks were pressured into making risky loans with the short-term goal of propping up parts of the economy. Now, many of the recipients of those loans, often small- to mid-sized businesses with narrow profit margins, are having trouble keeping up with the payments.

We have seen a big increase in European corporations coming to Iran, although inflow of foreign portfolio investment is still slow. It's better than it was, but it is still slow. Ramin Rabii CEO of Turquoise Partners