Quarterly profits at StatoilHydro were up 37%
State-controlled Norwegian oil and gas group StatoilHydro has agreed not to make any new investments in Iran.
The company is reported to have come under pressure from the US, which is trying to get Iran to halt its nuclear activities.
StatoilHydro is a key contractor and shareholder in the development of the South Pars gas field in Iran.
It said it would fulfil its obligations in the development and then gradually disengage itself from the project.
"We are attentive to the situation in and around Iran, and to the applicable laws and regulations of the European Union and the United States," said chief executive Helge Lund.
The US and EU suspect that Iran is trying to develop nuclear weapons, although Iran insists that its nuclear programme is only generating energy.
The announcement came on the day StatoilHydro released three-month results.
Net profit between April and June came in at 18.77bn kroner ($3.65bn; £1.85bn), up 37% on the same period in 2007.