That's going to be a bit unlikely, to say the least. (Assuming that, by after the conquest of Gaul, you meant as well after the Civil War : there's no way Caesar would go on a wild goose chase in Germania instead).
First, Germania, contrary to Gaul, isn't really known to Romans : politically, they don't have allies there, they don't really know what to expect both as resistance, but as gain. Gaul is indeed a really wealthy region, an important market place for Roman traders and a lot to gain not only as fame but from spoils of war.
Germany...Not so much.
Then, Gaul was quite develloped at this point : not only economically (which mean relatively easy supply) but as well on infrastructures. Caesar's armies never had any big problem on moving thanks to the gallic road network (on which later roman roads in Gaul were based on). Safe in southern Germania, under the Danube, this simply doesn't exist beyond the Rhine.
Giving that Roman bases are litteraly on the other side of Rhine and Rhone, it means really long supply lines, after Gaul went damaged by war as well that southern Germania (due to the economical and structural ruptures, we know Celtic peoples of southern Germania went trough some crisis).
It's really not about the strength of Germania's peoples*, but because Germania is an hard region to get (
without even getting on the topic of an Elbe border, which is really arbitrary and not that efficient, at least IMO), especially in the wake of a long war in Gaul, then a civil war.
*Rather than "Germanic peoples", mostly because the ethnic differenciation between Celts and Germans is essentially a by-product of Roman conquest : in fact ethnic separations were mostly blurred and many western and southern Germania's peoples importantly celtized (if not Celts) as Arioviste's Suevi.
Now I think we may disagree with Caesar's ambitions there : he didn't want to conquer Britain and create settlement there, but to make a point and prevent support from closely related peoples to continental Celts (especially in Belgica).
Similarily , his expedition in the other side of the Rhine was to prevent the peoples and tribal confederations to meddle with his conquest of Gaul, and to possibly clientelize them (would it be only to furnish a Germanic cavalry as IOTL).