Barcelona's Messi and Real Madrid's Ronaldo are widely regarded to be the best two footballers in world football at this moment in time.
Having scored nine goals in the last 27 days, Tottenham Hotspur winger Bale has since been compared to the Spain-based duo.
Despite describing Bale as "unstoppable", Owen has insisted that the Wales international is not as good as those two just yet.
"What a game that was last night. Bale is unstoppable at present. Has to be favourite to win The PFA Player of The Year Award," Owen wrote on Twitter.
"Quite a few players can score a goal like his matchwinner last night but very few can do it 'at will' like he seems to be doing at present.
"In Messi's or Ronaldo's league? Not for me just yet but certainly in the chasing pack and is young enough to keep improving."
Bale has scored 19 goals in all competitions this season.