“We have mobilized all of the country’s resources and are selling oil in the ‘gray market’,” IRNA quoted Zamaninia as saying.
The United States, which last year withdrew from the 2015 Iran nuclear deal with world powers, told buyers of Iranian oil to stop purchases by May 1 or face sanctions.
Iran says it will continue to export oil despite US sanctions, which are part of a campaign by Washington to mount “maximum pressure” on Tehran over its missile program and regional role.
“We certainly won’t sell 2.5 million barrels per day as under the (nuclear deal),” he said, giving no figures for current sales.
“We will need to make serious decisions about our financial and economic management, and the government is working on that.
“This is not smuggling. This is countering sanctions which we do not see as just or legitimate,” Zamaninia said.
President Hassan Rouhani on Saturday called for countering US sanctions by continuing to export oil as well as boosting non-oil exports.
Rouhani vowed that Iran will continue to supply oil to its major customers despite the unilateral measures adopted by the United States.
Reuters and AFP contributed to this story.