Prime Minister Prayut Chan-o-cha insisted it was necessary to remove Somchai Srisutthiyakorn as an election commissioner as Mr Somchai had "created confusion over the timing of the election".
He said the dismissal order made public on Monday was justifiable.
"We're going to have an election but his comments are confusing people. Is Mr Somchai the authority setting the election date?" he said.
As a result of the confusion, uncertainty has reigned over who has such authority -- the government, the National Council for Peace and Order (NCPO) or the Election Commission (EC), the prime minister said.
Only when the election date is set will the EC prepare for the poll. No talk should circulate that might create the wrong impression that the EC can determine when the poll will take place, Gen Prayut said.
"I've said the election will occur no later than February next year. That's that. There shouldn't be any more talk or discussion about it," he said.
Mr Somchai denied he confused the public with his political comments which the NCPO cited as the reason to dismiss him.
Speaking to the media for the first time since his sacking was made public on Monday, Mr Somchai insisted he said nothing that confused anyone. He said many of his comments and warnings about political events have turned out to be true.
Mr Somchai was removed as a commissioner by the NCPO for "inappropriate conduct" in an order published in the Royal Gazette and announced on Monday.
According to the order signed by Gen Prayut in his capacity as the NCPO chief, Mr Somchai was not fit to serve as an EC member.
Personal opinions he expressed were deemed to have caused confusion at a critical time, it said.
Moreover, Mr Somchai applied for the post of EC secretary-general without resigning from the commission first which suggested a conflict of interest, putting the EC's integrity in doubt, according to the order.
