President Hassan Rouhani slammed on Wednesday mixed messages of the Trump administration as unacceptable.
According to the Iranian president, the US is saying in private that they're willing to talks while saying in public they will intensify sanctions.
The statement comes several days after Rouhani said that the United States had offered to drop all sanctions against Iran in exchange for negotiations.
The same day, however, US President Donald Trump refuted claims, saying that it was the Iranian side asking for restrictions to be cancelled, but he refused to do so.
The development comes as US Secretary of State Mike Pompeo said in late-September that Washington wouldn't stop slapping sanctions on the Islamic Republic.
Relations between the US and Iran that have always been strained escalated after the US had decided to unilaterally withdraw from the 2015 Joint Comprehensive Plan of Action (JCPOA), reimposing sanctions against the Middle Eastern nation.
A new blow to the bilateral relations occurred earlier this year following a string of dangerous incidents in the Persian Gulf, including tanker sabotage attacks, ship seizures and the most recent - the attack on Saudi Arabia's oil facilities.
Although Yemen's Houthi movement has claimed responsibility for the attacks, the United States and Saudi Arabia have put the blame on Iran. Tehran has denied having any role in the incident.