The Gunners have signed just one player so far, but the Frenchman has suggested the North London club will be moving to buy players before deadline day comes and goes.
The Gunners are yet to sign a marquee player, despite pursuing Gonzalo Higuain, who left Real Madrid for Napoli, and continuing to monitor the situation of Liverpool forward Luis Suarez.
Yaya Sanogo, who joined the club from Auxerre, is Wenger's only summer signing thus far, but the Frenchman is hopeful of making more additions before the deadline passes.
"We are active," Wenger told the club's official website. "We are in a situation like Manchester United, like Chelsea, where everybody expects signings and at the moment not a lot has happened.
"There are 18 days to go, so that is a long time in the transfer market and we will be active.
"I cannot certify what the number [of new signings will be], but we will be active until the end, that is for sure."
Arsenal kicks off its Premier League campaign with a clash with Aston Villa at the Emirates Stadium on Saturday.