Billionaire Indian steel magnate Mittal was quoted in Saturday's British newspapers as saying that he would be making a bid for full control of the London club on Monday.
Formula One supremo Ecclestone, who holds approximately 62 percent of the club's shares, told Reuters at the Spanish Grand Prix that was not a given.
"Mittal put a statement out to say he was going to buy all the shares on Monday," the 80-year-old said with a smile in the Barcelona paddock.
"But it's a bit like these Murdoch people saying they're going to buy CVC (Formula One's commercial rights holders). They've forgotten to ask if it's for sale."
Ecclestone, a Chelsea fan, became the majority shareholder in December after buying out his friend and former Renault team boss Flavio Briatore.
He has said he has an agreement to give Italian Briatore first refusal should he wish to sell his stake.
Ecclestone, Mittal and Briatore joined forces in 2007 to buy QPR. The club secured promotion to the Premier League as Championship winners late last month.
Ecclestone said there was no question about Warnock staying, despite media speculation that the club might replace him with a high-profile Italian coach.
World Cup-winning manager Marcello Lippi, Ireland coach Giovanni Trapattoni and former Chelsea manager Claudio Ranieri have all been mentioned.
"Yes, 100 percent. We've never discussed anything about him leaving," said Ecclestone when asked whether Warnock would stay.
"He's never wanted to leave and we don't want to get rid of him."
