Benzema has been constantly linked with a move to Emirates throughout the summer, but appeared to bring speculation to an end last Monday after reiterating his happiness at Real Madrid.
While Giroud admits a move for Benzema remains unlikely, he has admitted his France compatriot would have been an effective addition for the north London side.
“The coach [Wenger] knows very well what he is doing, and sometimes you should not buy just to buy, and sometimes there are not players out there that you need, who are available,” Giroud told beIN Sports.
“We have a very good squad, with quality, and I am sure that with this squad we can go very far. But it would have been good if Karim had signed too.”
Benzema is one of a long line of strikers who have been linked with a move to the Gunners recently, with Alexandre Lacazette, Edinson Cavani and Luis Suarez rumoured to have been targeted.
However, Giroud has welcomed any potential striking competition, and has also dismissed any potential exit from the club himself.
“I would have been surprised if you had read a lot of things about my possibly leaving the club, because that was never on the table,” the 28-year-old said.
“Now, I am very good here, I say it, I repeat it. It is true that every year here there is speculation about a new striker signing.
“There were seasons when we signed [Alexis] Sanchez and [Danny] Welbeck, others when we were talking about [Luis] Suarez. It is obvious that in a club, a team, where a lot is expected, we need several good attackers and I understand that the fans want that we spend more money.”