Zidane also labelled praise given to him for the victory at Parc des Princes as "bullshit" because the Frenchman said criticism will soon return if his team's form dips.
Real crushed PSG 5-2 on aggregate to book their spot in the Champions League quarter-finals but Bale was named as a substitute in both legs of the tie.
Overlooked for Real's two biggest games of the season so far, the indication is Zidane does not trust Bale when it matters most.
But, asked what the Welshman lacks, Zidane said on Friday: "He does not lack anything, he's in a team where there are a lot of players, and he's doing well.
"With Gareth I have no problem, he's a fundamental player for us, very important, and he's going to play until the end of the season, like the rest."
Bale became the most capped British player in La Liga history last weekend when he passed David Beckham´s 116 appearances in the Spanish top flight.
He has an impressive 62 goals too in that time but since returning from a calf injury in November, the 28-year-old has not been an automatic starter.
"It is not a problem, I speak to him," Zidane said. "He knows where he is and that the others are important."
Zidane´s own future appears more secure following Real´s triumph in Paris, which pushes the club one step closer to an unprecedented third consecutive Champions League success.
But PSG coach Unai Emery has come under the same sort of pressure Zidane has faced this season, when Real were dumped out of the Copa del Rey by Leganes and fell adrift of Barcelona in La Liga.
"I do not want to convince anyone, everyone has their opinion, even when I win again, again, and again, because it's their opinion and I do not want to change that," Zidane said.
"That´s life, not to win, to lose sometimes. So today I am a better tactician than Emery? What bullshit, in fact, what bullshit. For me this is the biggest mistake.
"But hey, we have to accept it because in a few weeks we will say that I am stupid and that the other coach, as he won the match, he is better. That's the rule of the game."
Real travel to Eibar on Saturday and the Ipurua Municipal Stadium, which has a capacity of just over 7,000, the smallest in La Liga.
Zidane´s side sit third, seven points behind Atletico Madrid and 15 back on Barca.
"We have had good and bad matches, but my message to the squad is that they will not let their arms down," Zidane said.
"We will keep fighting until the end because in football everything can happen."