Bale's move to the Spanish capital has been widely flagged in Spanish and British media and is said to be worth 99 million euros ($133 million), eclipsing the price of around 95 million Real paid Manchester United for Cristiano Ronaldo in 2009.
Photographs of Bale in the Spanish holiday resort of Marbella appeared in local media on Sunday, prompting speculation he will be presented at Real's Bernabeu stadium on Tuesday or Wednesday.
At a news conference on Sunday previewing Monday's La Liga game at Granada, Ancelotti was asked where Bale might fit into his team.
The Italian laughed and said he had not thought about it as he had "other problems at the moment".
"I understand it's a very interesting issue for everyone but I can't say anything because he is not a Real Madrid player right now," he added. "I am sorry but I can't reply."
Quizzed later by British journalists, he said there were two reasons why he did not want to discuss the issue publicly.
"First of all because Gareth Bale is not a Real Madrid player at this moment," Ancelotti said.
"The second because I need to have respect for my players and we are focused on our game tomorrow."
He said he did not know if Bale would be the final addition to Real's squad before the transfer window shuts.
"I need to have respect for the Spanish journalists who every day ask me this and I didn't answer," Ancelotti said. "So for you it's the same I don't want to answer."
Ancelotti also responded to criticism from Barcelona's new coach Gerardo Martino about Bale's price tag.
Martino told a news conference on Saturday spending that amount of money on a soccer player would be "out of place in the current economic climate" and "a lack of respect to the world in general".
"They were words I didn't understand," Ancelotti said.
"He (Martino) has not been here for long and he still doesn't understand how European football works.
"He also doesn't understand his own club because Barcelona has spent money on some very important players.
"I don't want to talk about this but I think his words were a little strange."
Champions Barca will be without the injured Lionel Messi when they play their second league match of the campaign at Malaga later on Sunday. ($1 = 0.7461 euros)
(Reporting by Iain Rogers, editing by Pritha Sarkar)
