"Our position is that demand and supply are balanced and there is no need to increase oil to the market," Gholamhossein Nozari, Iran's oil minister, said.
Net import countries such as the United States have put pressure on Opec to increase oil supplies to arrest steep price rises for crude oil.
Oil prices topped more than $99 a barrel on November 21, but have reduced about $11 a barrel in the two weeks before Opec met.
The prices dropped amid expectations of increased oil output from the United Arab Emirates, as well as reduced demand growth forecasts from both Opec and the International Energy Agency.
A new US intelligence report that concluded Iran has halted its nuclear weapons development programme in 2003 is also helping to prevent steep oil price rises.
Prices increased by a dollar, to $89.32 a barrel, after the news that there would be no increase in oil supplies.
Some Opec members share concerns of consumer countries about the impact of high energy costs on economic growth, particularly as a US economic slowdown threatens to hit the global economy.
Opec ministers say they cannot control prices because speculators have separated prices from the fundamentals of the oil market.