The striker was handed the Football Association punishment last week after an investigation into a pre-season fracas at Mansfield Town in July.
Forestieri, and Mansfield’s Jacob Mellis, admitted to misconduct charges and the Owls forward was also fined £25,000.
He will miss a busy week for the Owls, who host Stoke City tomorrow before trips to Nottingham Forest and Aston Villa.
“It was a situation we did not expect,” said Owls boss Luhukay. “Three games is hard, first for Fernando and of course also for us.
“We now have three games where Fernando can’t play for us, but we must respect the decision from the federation.
“There’s nothing we can do now. We have to accept it and must look after the Villa game where Fernando can come back into the team.
“He will train this week and also some extra training next week.
“Every day he does very intensive work, not just in training but also individually and that is very positive. He is working hard to find a way back to the team.”
Wednesday will be looking to make it four successive Championship wins against Stoke tomorrow after maximum points against Millwall, Ipswich Town and Reading before the international break.
Luhukay is also without Kieran Lee, Sam Winnall, Gary Hooper and Sam Hutchinson, but could give debuts to loan signings, defender Michael Hector (from Chelsea) and midfielder Josh Onomah (Tottenham).
Both have been away on international duty and only trained with their new team-mates for the first time yesterday.
Onomah faces competition for a central midfield spot with Joey Pelupessy and Barry Bannan impressing in Wednesday’s winning run.
While Bannan has earned the plaudits – capped off with a stunning goal against Millwall – Luhukay has been delighted with the form of his fellow Dutchman, 25-year-old Pelupessy.
“Joey makes Barry Bannan better,” said Luhukay. “Barry has fantastic quality when we have the ball in offensive situations, but Joey will always cover him at the back.
“For example, when Barry goes offensive Joey takes his position to fight and to work for Barry when we lose the ball.
“Joey plays completely for the team, but he also stays behind Barry always to support him. Barry has different qualities, but it is important we don’t have two Barry Bannans in the midfield. It is why it is a good balance between both.
“He is a team player. Sometimes these players from the outside are not so spectacular. He maybe doesn’t give the last ball or go past two or three players and make something special
“His quality is he does important work for the team. He wins ball, wins one-on-ones and to anticipate counter attacks from the opponents.”
The Owls welcome a Stoke side to Hillsborough for the first league meeting between the two clubs in over a decade.
The visitors, relegated from the Premier League in May, have struggled to adapt to the Championship, winning just once in six outings.
Not that Luhukay is taking the visitors – who boast a squad brimming with quality in such as Jack Butland, Ryan Shawcross, Joe Allen and Saido Berahino – lightly. “Stoke is a high challenge for us,” said Luhukay.
“They are a team who have come down from the Premier League. They have struggled a little bit at the beginning of the Championship season. We know the quality is there, but we also have our own quality and we must bring it on the field.”