Tisdale told BBC Radio Devon: "It's a very difficult situation for a young man who's unsettled.
"Ryan's had lots of interest but hopefully by the end of January that can all seep away."
Tisdale continued: "We don't want Ryan to go.
We've fought off offers for him
and because he's out of contract in the summer- people will make poor offers because they think we're desperate for the money - well we're not.
"I'd rather have Ryan until the end of the year but during the month of January it's very difficult for him, for his family and I want him to be with us.
Harley missed out on both of Exeter's recent trips to Brentford in the league and Johnstone's Paint Trophy, games which both ended in a 1-1 draw.
Tisdale said: "Hopefully he's able to stay with us until the end of the year and he'll get his head back onto doing his job.
"Hopefully he'll have a few things ready for him in the summer and he can concentrate on playing for us until the end of the season."
Source: BBC Sport
Source: BBC Sport