The 32-year-old has signed with the Scottish Premiership club until the end of the season, after which he hopes to be heading to Brazil with Cameroon.
Djemba-Djemba, who was released by Partizan Belgrade just before Christmas, said: "Why not? I just need to be good on the pitch, enjoy myself, play well with my new team-mates and I hope the manager of Cameroon will think about me."
The former Aston Villa player won his most recent cap two years ago but he is aiming to impress German manager Volker Finke, who took charge in May.
"You know in Cameroon we change managers like we change shirts," he said. "I hope he will think about me if he needs my experience.
"I played in the team for eight and a half years from 2001. So if he needs me I will be happy to pull on the Cameroon shirt, because it's a dream for everyone. I hope he will think about it.
"But the decision is in my hands - to work, play and try to be called up for the World Cup."
The combative midfielder joined United in 2003 in a £3.5million move from Nantes, but moved on to Aston Villa after 39 appearances. He was loaned to Burnley during his spell with Villa and has since played for Qatar SC, Odense and Hapoel Tel Aviv before moving to Serbia last summer.
And he is excited to be back in Britain.
"For me it's a great league and they are also in the cup so it's a good challenge for me," he said.
"For me, the Scottish league is similar to the English league so it's a great move for me. African people will see me in British football so I like that. It will not be new for me to be on the pitch and tackle left and right."
Djemba-Djemba is following in the footsteps of former United boss Sir Alex Ferguson, who managed St Mirren in the 1970s.
"I was told that yesterday and I was surprised," he said. "I hope he will come to see me play."
Ferguson might have to wait until after Sunday's William Hill Scottish Cup clash with Dundee United to see his former player in action though as Djemba-Djemba rated his chances of making the Tannadice clash at "40-60" ahead of his first training session.
"I need some training to be 100 per cent fit and get 90 minutes in my legs," he said. "But I have a few days to train and I will see what the manager decides. Any decision the manager takes, I will respect it."
Meanwhile, Saints defender Marc McAusland has lost his appeal against his red card in their 2-1 defeat by Hearts last week. The centre-back will miss the Scottish Premiership game against Aberdeen on February 15.