"I don't know how true it is. But when there's such an allegation, can a wise man trust you?" Ayatollah Ali Khamenei tweeted.
Both the U.S. and Iran have said they will no longer adhere to the Obama-era Joint Comprehensive Plan of Action.
The Hawaii congresswoman and Democratic presidential candidate said Trump is "putting all Americans in greater danger."
Johnson's comments to Iran's president came after Trump urged European allies, as well as Russia and China, to withdraw from the 2015 treaty.
Robert Malley argued that Trump's policies towards Iran have put Americans "more at risk than they were before" he came into office.
Retired U.S. Ambassador John Limbert warned that President Trump had "no plan" and this could lead to a "disaster."
"In the world of politics, all things affect each other," Iran's foreign ministry spokesperson said Sunday.
The president should do all he can to avoid getting the United States into an "intractable entanglement" with Iran, the New York Times editorial board wrote.
"We need to be very careful as we move forward," Representative Mark Green cautioned.
Season 3 of "The Marvelous Mrs Maisel" is here.
This week marks the 40th anniversary of the storming of the U.S. embassy in Tehran, an event that marked the start of a decades-long stand off between Washington and Iran.
An Iranian government spokesperson blamed the "bullying policy" of the U.S. and the "lack of resistance" by the Europeans,
Iran is widely expected to make extensive use of its special operation forces and regional proxy militias in a hypothetical future war with the U.S.
Knowing the context of what happened in 1979 is crucial to our ability to move forward.
Two Iranians, Ali Nafarieh and Mohammad Ali Babapour, have been sentenced to 10 years imprisonment on charges of spying for the U.S. A third unidentified person has been sentenced to death.
"Iran wanted me to lift the sanctions imposed on them in order to meet. I said, of course, NO!" President Trump tweeted Friday.
The energy secretary said Iran "could pay a very dear price economically" but added that Trump is "not interested in going to war."
"Number two: I think the president should stop tweeting altogether about this and stop making off-the-cuff remarks," Senator Angus King said.
"Such [American] comments and measures are more akin to the plots hatched by secret and intelligence services for damaging the image of a state to prepare the ground for a series of [hostile] measures," the Iranian Foreign Ministry said.
With diplomacy on the horizon, activists are continuing to call for democratic change in Iran—but that doesn't mean they want U.S. intervention.
"They would appear when they are needed to strike a tough blow to the enemy," General Mohammad Hossein Dadras warned.
Iran came on the French Government's invitation, but will not be meeting the American delegation as tension escalates between the two countries
Trump may not court a war, but he is doing too little to avoid one. He needs to act fast.
"Trump needs to know that as long as he speaks the language of coercion with a civilized nation, they will only grow closer and more unified," Iran's Parliament Speaker Ali Larijani said.
A leading opponent to the Iran nuclear deal, Israel has now threatened to go to war if Tehran does not abide by its restrictions.
An attempt by the European Union to keep Iran in compliance with a 2015 nuclear deal may have fallen short.
Trump's freewheeling remarks to reporters came after the president made the last-minute decision to call off an approved airstrike on Thursday
It is not yet clear whether the country is violating the terms of the Iran deal, known formally as the Joint Comprehensive Plan of Action (JCPOA).
Iran's leaders are demanding that their European counterparts do more to save the deal.
Britain's foreign secretary, Jeremy Hunt, urged Washington and Tehran to defuse tension to avoid destabilizing the Gulf region.