Darioush Rezaie, 35, a university lecturer, was killed by gunmen in eastern Tehran on Saturday. Some media reports said Rezaie was a nuclear scientist but Deputy Interior Minister Safarali Baratlou said this was not true.
Parliament Speaker Ali Larijani blamed the United States and Israel for the killing.
“We were not involved,” said State Department spokeswoman Victoria Nuland, expressing US sympathy to Rezaie’s family.
“We hope that Tehran is not planning to use this incident to distract attention from what it needs to do, which is to come back into compliance with international obligations.”