Carlos Queiroz's team have been drawn alongside Bosnia-Herzegovina, Nigeria and Argentina, the latter of whom are ranked among the favourites to the lift the trophy.
Beitashour has already written off Iran's chances of finishing top of Group F, acknowledging that Argentina are likely to occupy that spot.
His side get their campaign under way against Nigeria on Monday and the USA-born full-back believes that there is little to separate the three less-fancied teams in the group.
"I definitely think Argentina is the favourite (to win the group)," he said. "They do deserve it.
"They've been a great team, and they've not been hyped for nothing. I think everyone expects that out of them, but I think the second spot of our group is up for grabs.
"We've got three hungry teams that are trying to win it, so that's why it's so important for that first game to start off on the right foot.
"When we were about to land in Brazil, just seeing the country, that feeling right there, I'll never forget it.
"It's been really exciting and great every day we've been here, and I'm excited for the 16th (Monday) to come up."
