In November 2020, an interview of Kalantari was published on social media, in which he called Ayatollah Khomeini an ungrateful child used by Britain and the United States to overthrow the Pahlavi regime.

In the interview, which, according to Kalantari, dates back to at least three years before its release, the reporter asked if he thought negotiations had taken place between Khomeini and the Americans, to which Kalantari replied: "I do not know. I do not have information about that. It is not far-fetched to say that Imam Khomeini was their ungrateful child. They stopped supporting the Shah, and Imam Khomeini took advantage of the opportunity."

Following the widespread publication of the video on social media, the judiciary filed a case against Kalantari on two charges: "insulting the founder of the Islamic Republic" and "spreading lies with the intention of disturbing the public opinion." He was summoned to the court for government officials and was released on bail.

Kalantari officially apologized after hardliners protested at his interview. But on March 9, 2021, Branch 26 of the Revolutionary Court sentenced him to four months in prison and banned him from membership in political parties and groups for two years. As part of this case, Kalantari was also sentenced by Branch 1058 of the Criminal Court to pay a fine of 40 million rials for spreading lies.

This sentence is still under appeal and has not been finalized.