Backed by wealthy new owners Qatar Investment Authority, PSG invested heavily in the squad last summer by bringing in the likes of Zlatan Ibrahimovic, Thiago Motta and Ezequiel Lavezzi.
Coach Carlo Ancelotti has suggested there will be no more new faces at the club during this transfer window with the exception of Brazilian midfielder Lucas Moura, who had already agreed a deal to join from Sao Paulo.
However, Leonardo says they may be persuaded to sign more players should any current names depart the Parc des Princes.
"The transfer window is always strange, you never know what can happen," he said in quotes reported in L'Equipe.
"We need to see whether players will leave, then we will look at the issue.
"If things stay as they are, we will not touch anything and then Lucas will be the only signing. But if players leave and there are opportunities, then we'll see.
"There are players like (Guillaume) Hoarau, Nene, (Diego) Lugano, (Siaka) Tiene and (Mohamed) Sissoko who could leave and we will see what happens in the coming days."
Meanwhile, Lavezzi, Lugano and Javier Pastore could face disciplinary action after reporting back to training late following the Christmas break.
The club are currently at a training camp in Qatar, but the trio delayed their arrival in the Middle East much to the anger of Leonardo.
"Lugano, Lavezzi and Pastore arrived a day late and I'm not happy," said the Brazilian.
"This is not good and it was not planned. I have not met with them yet but we'll see what has to be done."