Sanctions on Iranian crude exports will likely succeed in hurting the country's economy, but whether the U.S. will achieve its goal in pushing for changes from the current regime in Tehran remains questionable, an expert told CNBC last week.

National Security Advisor John Bolton has said the American policy for Iran is to push for behavior change from the current regime, but not to oust it. However, forcing any real changes will be a challenge, according to Emily Hawthorne, Middle East and North Africa analyst at geopolitical think tank Stratfor.

Instead, Iran is likely to consider negotiating with the U.S. only when it runs out of other options, she said.

"We are already seeing a very significant effect in Iran in terms of the economic power of these sanctions," Hawthorne said. But, she added it's a "very big open question" whether "the U.S. administration going to see the type of behavior change from Iran they are wanting to bring about through using these sanctions as a tool."

"Over time it is going to become more likely that Iran does consider a negotiation with the U.S. as economic pressure increases, but for now, they are going to try and rely on all of those channels that include their allies, the countries that agree with them politically," she said. "They are going to go through all those avenues in order to avoid working directly with the United States, whom they don't think is giving them a fair negotiation."

For its part, Washington is looking for a stronger deal than what had been made with Iran in the past, Hawthorn said.

She said the U.S. "views the Iran nuclear deal signed in 2015, implemented in 2016, as not being sufficient to control things like ballistic missiles and support for militias. So they are trying to negotiate something stronger, something that might be more of a treaty, something that might be something that actually requires signatures are not just an agreement on a plan of action."

The administration of U.S. President Donald Trump last week continued its vocal rejection of multilateral bodies after it withdrew from an International Court of Justice (ICJ) protocol and pulled out of a 1955 friendship treaty with Iran.

The moves were triggered by an ICJ ruling that Washington must ensure its sanctions don't hit humanitarian aid or civil aviation safety for Iran — a ruling that is binding but cannot be enforced.

—CNBC's Natasha Turak and Reuters contributed to this report.