Queiroz, who had an ill-fated spell at the Bernabeu in 2003-04 and also served as Sir Alex Ferguson's assistant at Manchester United, has been in charge of Iran since 2011.
The middle-eastern nation were the first Asian team to qualify for Russia 2018, but after being drawn against Portugal, Spain and Morocco in Group B Queiroz laid out a stark choice for those in charge.
"I'm here to say Iran needs a special local preparation," the coach said on a video posted on his official Facebook page.
"I don't care about the threats and what they have been trying to do to stop me talking. The Iranians fans deserve a special World Cup preparation.
"We need to implement a special preparation to bring honour and pride.
"They can fire me, I don't care, but it's time to express my opinion because the Iranian fans deserve that and the players deserve full support to be ready to compete in this competition."
The Portuguese coach has worked wonders with Iran since his appointment, taking the nation to consecutive World Cups for the first time in their history in 2014 and 2018.
But his tenure has also been marked with clashes with the local FA, handing in his resignation on several occasions due to disagreements.
His current contract, signed in the wake of first round elimination in the 2014 World Cup, runs until the end of the Russia tournament.