Iran's agreement to freeze its nuclear program for six months in exchange for limited sanctions relief could lead to more oil on the world market and lower prices at the gas pump, said Kevin Book, managing director at ClearView Energy Partners.
"In the long-run, ... this suggests a bearish trajectory" for prices, Book said on CNBC's "Squawk Box" on Monday, following the weekend deal between Iran and six world powers—the U.S., China, Russia, France, Britain and Germany.
(Read more: Brent eyes $105 asIran deal eases supply risks)
In the White House fact sheet, the deal allows for a 1 million barrel-a-day limit on Iranian oil exports. A recent estimate said Iran exported 715,000 barrels per day in October.
"I brought some rose-colored glasses," Book said, putting on sunglasses with a rosy hue during his CNBC appearance. "A million barrels a day of Iranian crude the world forgot could come back. So that would be a dramatic shift in prices, and that would flow through to the American consumer."
(Read more: Iran oil, energy sanctions still in force: US)
But as the holiday travel season approaches, the trend for gas prices is more dependent on unstable Libya than on Iran.
"Libya's got a million barrels off line right now. Libya is going to go out of business as a country if they don't solve this problem in the next six months or so," Book said. "Chances are they won't solve it before the end of the year. So I would expect gasoline prices to stay about the same" for the upcoming busy travel time.
(Counterpoint: Why gas prices will go higher, despite Iran deal)