Commons believes the Hoops must sign a forward who will deliver between 20 and 30 goals per season.
The 30-year-old midfielder is disappointed they have not yet replaced Gary Hooper, who left Celtic Park last summer to join Premier League Norwich.
Before leaving, Hooper scored 31 goals during the last campaign, with Teemu Pukki and Amido Balde moving to Celtic as his replacements during pre-season.
Commons has netted 12 goals this season and, despite the club being runaway leaders in Scotland, they only registered three goals from their six Champions League group games this season.
"I think when you are relying on people, midfield quality to get you goals then once they dry up you are looking for a striker," he said in the wake of Celtic's 6-1 drubbing at the hands of Barcelona in the Nou Camp.
"In a Celtic team you are looking for a striker to get between 20 and 30 goals a season and at the minute we haven't quite got that.
"I know people are working hard on and off the field to try and get us the goals but replacing someone like Gary Hooper is going to cost you between six and 10 million and, at the minute, we are not willing to spend that."