Suzu made a good point.

Why send in your best when the gennin's could do it? Plus, to save ONE gennin?

Plus she didn't only send in only the leaf gennins, she send in the sand gennins as well. Thats 8 gennins (excluding Rock Lee)..

Maybe it was a lack of information... but
With talents such as Neji, Naruto, GAARA, Shikamaru as their leader.. I'm sure even Jounnin's would have to think twice before attempting to go into a head on battle.

Plus, it was a chase. Where as time passes on, Sasuke was getting further and further away.

They didn't have time to assemble a Jounnin team. Because all were out doing some other missions.