The Baggies tasted defeat in the Championship for the first time this season when they were beaten at Stoke on Friday night.
Speaking after that match, Ismael admitted The Potters thoroughly deserved their win with Albion having been second best all over the park.
And the boss believes tiredness may have been one reason his side underperformed.
“The energy was not there to get the result what we wanted,” Ismael said.
“We need to learn, we are frustrated because we wanted more.
“We will come back with a big motivation, we will work hard to put in a better performance – and we will put in a better performance – because we will be fresh against Birmingham.
“The aim is to bounce back straight away.”
Ismael, who celebrated his 46th birthday last week, flew to Germany to spend time with his wife and children following the Stoke game.
And he has told Albion’s players to also take a few days off and rest – both physically and mentally – ahead of the derby with Blues on October 15.
“The result at Stoke doesn’t change anything – we need to breathe, to recover,” the boss said.
“I haven’t seen my family for a number of weeks now.
“My only focus was West Brom.
“I need to see my family, to re-charge my batteries.
“And it’s exactly the same for the players.
“And we will come back fresh and ready to go again.
“We need to keep going, keep moving, keep working.”
Albion were outplayed by Stoke for long spells on Friday.
But when Sam Johnstone saved a 71st minute penalty from Sam Surridge, it looked as though the Baggies might escape with a point.
In the end, Nick Powell found a winner for the home side.
But Ismael was disappointed his side didn’t kick on following the penalty miss.
“That can normally give you a second energy and put doubt into the opponent,” Ismael said on Johnstone’s penalty save.
“But even the power wasn’t there like usual.
“I think it was tiredness. And now we need to learn from that and recover quick because this is the Championship.
“Stoke are the best team we have played this season so far and they deserved to win, it’s as simple as that. Our performance was not good enough.”