"Any disruption in the supply of crude oil … will lead to the intensification and prolongation of the economic recession (in consumer countries)," said Hojjatollah Ghanimifard.
Ghanimifard, a deputy director of the National Iranian Oil Company, was quoted by the semi-official Fars News Agency.
The United States is pushing for a fourth round of U.N. sanctions on Tehran over its refusal to halt sensitive atomic work the West suspects is aimed at making nuclear bombs, a charge Iran denies.
The latest draft proposals agreed by the United States, Britain, France and Germany include restrictions on new Iranian banks established abroad and on insurance of cargo shipments to and from Iran, the world's fifth-largest crude exporter.
They do not include sanctions targeting Iran's oil and gas sectors as the French had originally pushed for.
Energy-hungry Asian countries are the main buyers of Iranian oil, but recent months have seen a drift in Asia away from crude sourced from the Islamic Republic.
Reliance Industries will not renew a contract to import crude oil from Iran for financial year 2010, two sources familiar with the supply deal said on April 1.
Some trading sources said the move could be due to a price disagreement when the refiner has easy access to competing grades, while others said pressure from the United States and its allies may be another reason.
Japan's Iranian crude imports are also seen declining this year, while China's purchases from Iran fell nearly 40 percent in the first two months of the year.
Ghanimifard said any sanctions on Iran's oil sector would not be practical, suggesting the country could always find alternative buyers.
"One of the main reasons for the impracticality of such a sanction stems from the diversity and multiplicity of Iranian crude buyers which are spread all over the world," he said.
(Reporting by Hashem Kalantari; writing by Fredrik Dahl, editing by William Hardy)
