The comments by Deputy Foreign Minister Abbas Araghchi appeared tailored to address Iranian factions, including the powerful Revolutionary Guard, that have grown uneasy over fast-paced outreach last week between the White House and President Hassan Rowhani, which was capped by a 15-minute phone call with President Barack Obama.
''Definitely, a history of high tensions between Tehran and Washington will not go back to normal relations due to a phone call, meeting or negotiation,'' Araghchi was quoted by the semi-official Fars news agency as saying.
Hassan Rowhani seeks to restart stalled talks over its nuclear program in the hopes of easing U.S.-led sanctions. Iran, however, has not clarified what concessions it is willing to make with its nuclear program in exchange.
Araghchi also reiterated statements by Iran's Supreme Leader Ayatollah Ali Khamenei, who said he no longer opposes direct talks with Washington but is not optimistic about the potential outcome. Khamenei appears to have given Hassan Rowhani authority to handle the nuclear talks with world powers, scheduled to resume in Geneva in two weeks, and seek possible broader contacts with the Barack Obama administration.
''We never trust America 100 percent,'' said Araghchi. ''And, in the future, we will remain on the same path. We will never trust them 100 percent.''
The divisions over Hassan Rowhani's overtures were on display Saturday when he returned from New York. Supporters welcomed him with cheers, but a smaller pocket of protesters shouted insults.
The U.S. and Iran broke ties after the 1979 Islamic Revolution when mobs stormed the U.S. Embassy in Tehran. A total of 52 hostages were held for 444 days.
A hard-line lawmaker, Hamid Rasaei, criticized the phone call as ''breaking the resistance brand'' of Iran - a reference to the self-promoted idea that Iran is the anchor for opposition to Israel and Western influence in the region.
He said acceptance of Obama's phone call by Hassan Rowhani was ''undignified'' and allowed the U.S. to claim Iran seeks to modify its policies.
''You converted a win-lose game to a win-win one'' for the U.S., he said during a parliament session Sunday.
Another conservative lawmaker, Alaeddin Boroujerdi, head of the influential parliamentary committee, saw the phone call as Hassan Rowhani trying to help the ''failing reputation'' of Obama.
The core of the opposition to Hassan Rowhani appears built around supporters of former President Mahmoud Ahmadinejad, who once sent a letter to then-President George W. Bush in an attempt to open dialogue. Ahmadinejad apparently was rebuffed by Bush, and the former president later fell from favor with Khamenei after trying to challenge his authority.
Khamenei's presumed nod to Hassan Rowhani to test outreach with Washington may be seen by Ahmadinejad's backers as another slap to the former president.
Ahmadinejad's first public comments on the Barack Obama phone call carried a noncommittal tone. ''I don't know, maybe it was the right thing to do,'' the conservative Baztab news website reported him as saying Sunday.
On the flip side, the phone call brought jokes circulating in Iran by text message.
''I know Hassan Rowhani called Barack Obama first,'' read one. ''Then Barack Obama told him, `It's better that I call you since you are under sanctions and your call may cost a lot.'''