The 29-year-old Northern Irishman, whose contract at Ashton Gate expires at the end of the season, has made only three appearances for the Robins this campaign, and has been loaned out for a month to the Glovers in League One.
Sproule told the Bristol Evening Post: "I do not think my future is going to be at Bristol City by the summer, but I have had a fantastic time at Bristol City.
"It has been very frustrating for me. I started the season brightly at Bristol. That was under Steve Coppell, so I was looking forward to a good season, but that is football for you.
"I am still a signed player there and, if called upon, I would give 100% for them again but at the minute I have to concentrate on playing for Yeovil. I want to get my match sharpness and, hopefully, my career can get sorted out, if it is not in January then in the summer."
Bristol City boss Keith Millen added that Sproule remains in his thoughts for the current Championship campaign: "I'm going to need to be able to call on a full squad for what is going to be a very busy period. That's why Ivan is only going (to Yeovil) for four weeks. He will be back in time for Christmas."