If you meant the OPEC then,
Dude, that's one of the basic's of economy,
In a market (In economy is called the "perfect market") where there are lots of players with each one holding a small share of the total market, and every player trying to maximize it's own profit function, prices will drastically fall in the favor of the consumers and the producers are the one's to endure the biggest losses, not to let this situation to happen, the solution is for the producers (a number of the producers) to start a form of union to make consistent and united policy, in economy, such a player is considered to have "market power" and would be named "price maker" and others are called the "price takers".
Where there is not a regulatory unit, such a market is considered the ideal market for producers.(for both the price maker and the price takers)
Iran and others have traditionally tried to form such a player (one who holds the market power) but the consumers (US, EU, ...) have always tried their best to break the monopoly of this price maker (Called the OPEC) by enforcing it to compete with another significant big player (Now that one is the Saudi Arabia) in order to reduce the prices.