The Italian revealed that the Welsh winger will be out for Madrid's game against Levante at the weekend, but claimed he will be fully fit to return after the international break
Madrid overcame the Danish champions with a double apiece from from Cristiano Ronaldo and Angel Di Maria, but Bale was forced to watch on from the sidelines as he recovers from a thigh injury.
Ancelotti revealed that the €100 million summer signing from Tottenham will miss the weekend trip to Levante, but believes the 24-year-old can catch up with his team-mates during the subsequent stop in domestic action for World Cup qualifiers.
"It wasn't possible for him to play," the Italian coach explained. "He had a knock and we did an X-ray, but it didn't show up anything special. We are waiting for him to recover.
"He has not been 100 per cent, but after two weeks he will be in top shape. It's normal he is not happy - he wants to play. He is very excited and it's not a problem - now there is time for him to reach optimum fitness and to avoid [further] injuries."
Ancelotti, meanwhile, was happy with Madrid's reaction following Saturday's derby defeat at home to Atletico.
"It was a good game," he said. "We started well, with intensity and balance. Then, after Cristiano's [first] goal, we were slower, but we recovered our intensity and scored some more goals late on. The team's attitude was good.
"We tried to play with Cristiano and Di Maria more open, and create more chances from crosses. The first and second goals were good combinations and we made use of the wings. The three midfielders, [Asier] Illarramendi, [Sami] Khedira and [Luka] Modric, all had good games."