The world's most expensive player came off the bench to win Los Blancos a penalty in their 2-0 victory over Malaga on Saturday - his first appearance since the Madrid derby almost three weeks ago.
Reports had claimed that the Welshman was sidelined with a slipped disc in his back, but Bale has insisted that it was only a "minor" muscle strain that was preventing him from playing.
"It was just a little thigh strain that was blown massively out of proportion," he told Real Madrid TV. "It is just a minor injury and I'm back now.
"I've not had a lot of game time, pre-season, training or running so you pick up little niggles. I have to take one step at a time. I've not had much training or games. It's all about building me up now."
Bale, 24, has scored one goal in four appearances for Real since joining them in an £85m move from Tottenham Hotspur this summer.