A senior Iranian member of parliament on Sunday harshly opposed the establishment of the American Iranian Council (AIC) in Tehran, ISNA news agency reported.
Washington last week granted permission for the New Jersey-based research and policy think tank group to set up an office in Tehran in what is widely believed to be an effort to improve ties after almost three decades of political hostility.
"The government should not issue permission for this office. (AIC head) Houshang Amir-Ahmadi is just a low-ranking dealer of the US and opening the office in Tehran would not be in line with national interests," Alaeddin Boroujerdi, the head of the parliament's foreign policy commission, told ISNA.
He said any efforts to improve ties should be done at a higher level than the AIC.
Tehran and Washington have had no diplomatic ties since 1980 and several efforts to improve relations have failed, but Iran hopes for changes following the November US presidential elections.

Shares fell 2.1 per cent Friday on the Seoul stock exchange on general recession fears. South Korea's won dropped against the dollar.
When the Spirit rover landed on Mars five years ago, no one expected it or its sister rover Opportunity to make it to their first birthdays, let alone their fifth.
Amelie Mauresmo fell victim to a leg injury after less than half an hour on court Friday to hand over a 4-0 victory which put French compatriot Marion Bartoli into the final of the Brisbane International.
Mumbai-based movie Slumdog Millionaire won five prizes Thursday night at the Critics Choice Awards, cementing its position as a surprise favourite just as the Oscar season moves into high gear.
After the Taipei Zoo received two giant pandas from China, another Taiwan zoo said Friday it is seeking to receive a pair of pandas from China.