The Posh have already smashed their transfer record this summer with the acquisition of Britt Assombalonga, who arrived at London Road for a fee believed to be in the region of £1.25m.
However, the 41-year-old, who has seen his side win all three of their games so far this season, admits that he is keen on adding further reinforcements.
Speaking to BBC Sport, Ferguson said: "I think we need the competition in the squad.
"One or two players will be going out, which means we'll be getting another one in.
"The chairman and I are working to make that happen, and I'll be very pleased if it does."
Peterborough coasted to a 4-2 victory over Notts County on Saturday, with club-record signing Assombalonga among the goalscorers.