Iranian Oil Minister Rostam Qasemi says Iran will soon reduce its oil exports to some countries.
And a member of Iran's Energy Commission, Emad Hosseini, is reported as saying Iran is considering banning all oil exports to the European Union for five to 15 years.
An EU ban on imports of Iranian oil comes into effect in July.
However, analysts say the world is likely to have more oil this year, with additional output from Saudi Arabia, Iraq and Libya making up for any lost from Iran.
China and India have made clear they are keen to take any spare Iranian oil.