Go ahead and smite at range!
With nothing else to say on the matter, the smite ability that's granted by the 6th-level Clr spell visage of the deity [trans] (Spell Compendium 230) does, indeed, seem to be compatible with a ranged attack that both requires an attack roll and targets a lone foe. This'll make it incompatible with other effects that occur at range—no smiting with the spell flame strike, for instance, no matter how appropriate that would be—, but this smite nonetheless appears to be one of the rare cases where a smite is usable at range.
The spell first appeared in appeared in Defenders of the Faith (May 2001) as aspect of the deity, was exclusive to the Mysticism domain therefore unavailable to clerics generally, and shares the most current version's lack of a melee-attack-only restriction, but does say that the caster "take[s] on all the qualities of a celestial or fiendish creature (see the Monster Manual for complete details)." This DM would be tempted to limit that smite to melee only as per the smite granted by the template celestial and fiendish (Monster Manual 31 and 107–8, respectively). Likewise, when the spell was updated for the 3.5 revision by Complete Divine, and its availability expanded, minor changes were made to the DR and SR the spell grants, but the spell continued to use Defenders' language referencing the Monster Manual, so, again, probably no ranged smite with that version, either.
It's the Spell Compendium that removes the Monster Manual reference from visage of the deity, the spell's description saying instead that the caster "take[s] on many qualities of a celestial or fiendish creature" (emphasis mine) then listing those qualities, no Monster Manual reference in sight. Thus, fairly definitively due to specific trumps general and perhaps by happy editorial accident, the spell now allows a ranged smite.
I can't justify this design decision except to say, "Meh." I looked at about 15 classes that have various kinds of smites and found none that allowed a smite with something other than a melee attack (cf. the feat Ranged Smite Evil from Book of Exalted Deeds 45, the elf paladin 1 substitution level supernatural ability ranged smite evil from Races of the Wild 155), yet the aspect of the deity spell's final version from the Spell Compendium apparently does. A lone ranged smite evil makes the spell an interesting buff for cleric-archers, but ask the DM if each individual casting of the visage spell has a separate the 1/day limit… the DM could rule they don't, that one use of a smite from a visage spell expends them all for that caster's visage spells for the day. (Such confusion sounds to me like a pretty strong reason not to write spells that have durations of 1 round/level that grant 1/day abilities, but nobody asked me.)
If a DM felt strongly enough about this—that a ranged smite was somehow terribly, terribly wrong or whatever—, I guess such a DM could use instead the Complete Divine version of the spell. I mean, the Spell Compendium's compilers did change several spells for no reason that I can discern (like the wall spells), and such changes are frustrating, but this DM wouldn't spend the effort. If a cleric 11 wants to cast the spell aspect of the deity instead of other 6th-level spells like blade barrier [evoc] (PH 205), energy immunity [abjur] (SpC 80), harm [necro] (PH 239), heal [necro] (PH 239), or superior resistance [abjur] (SpC 174), this DM's okay with the spell aspect of the deity granting the cleric 1/day a ranged smite.