Liverpool are top of the table with two points more than second-placed City, who have a game in hand.
"It's a great reason to be out the country when those two are going head-to-head for the title," Rooney, who now plays for Major League Soccer side DC United, told talkSPORT.
"I hope Man City get over the line before Liverpool. I couldn't bear to see them win it, it would be a nightmare for any Evertonian.
"I remember in 2005 (Liverpool) won the Champions League and they're still talking about it now so it would be another 10 or 15 years of that."
Liverpool have not won a league title in 29 years and ending that drought this season would allow them to move to 19 title wins in the English top flight, one behind United's record.
(Reporting by Hardik Vyas in Bengaluru, Editing by Simon Jennings)
