McInnes had wanted to buy a defender on a permanent basis before last Friday's transfer deadline, but he will now wait for the loan window to reopen on September 8.
"I'm hoping to have a new player in before we play Blackburn," he said. "I was hopeful of getting one in before the Barnsley game but, after a lot of to-ing and fro-ing, it did not happen.
"But I'm still hopeful of getting one when the window reopens, ideally before the end of the two-week international break."
Blackburn visit Ashton Gate on Saturday, September 15.