Trump has criticized the Iran deal very extensively, saying it should never have been made. Barbajosa said he expects a "significant decline" in oil prices, should the U.S. attempt to delay a decision on the deal in order to buy time.
"It's just pushing the decision further into the future, but that just means that that buffer of supply that is coming from Iran at present would continue to be there for an extended period of time," he said.
Analysts expect renewed sanctions to take out as many as 500,000 barrels of Iranian oil a day. That may have a limited impact on markets, but it would also hand other OPEC members a chance to increase production.
"OPEC might use this as an opportunity as an exit strategy from the current strategy of restrained supplies, because what we see is that there is little scope for them to start producing again at the levels they would like to produce without having a negative effect on prices," Barbajosa said.
"If Iran gets out of the market, it might be a very natural way for them to say, 'Oh, we need to increase production now, because Iran is no longer there,'" he said.
— CNBC's Tom DiChristopher contributed to this report.