The Arsenal forward is being linked with a host of clubs before the transfer window closes.
While reports in England have stated that Nketiah is likely to join Forest, Santo was non-committal.
“You know how this transfer window works, until the last day anything can happen,” he said when asked about Nketiah.
“I always insist and say that most important is to keep the players we have so we don’t get any kind of surprise.
“Every club will try in these last days to fix the final details of their squad. We are the same. What we have to be is ready to react.
“We are pleased with the players already here. The players who have joined have integrated really well, but it is never finished until the 30th.
“So many things are going on. These last days of the window are normally when clubs try to fix the final details, so anything can happen. Us as a club, we have to be ready to react for any situation.”