hey i´m making a divination wizard hobgoblin, and would like to know if it´s saving face feature also could work on spell attacks?

Saving Face

Hobgoblins are careful not to show weakness in front of their allies, for fear of losing status. If you miss with an attack roll or fail an ability check or a saving throw, you can gain a bonus to the roll equal to the number of allies you can see within 30 feet of you (maximum bonus of +5). Once you use this trait, you can’t use it again until you finish a short or long rest.

It says nothing about the attack roll being used for a weapon.

Elsewhere in the PHB you will see descriptions specifically state "weapon attack", this description does not.
So I'd say you are safe to use this feature with a spells that require an attack roll.

Yes it will apply to spells that have an attack roll. It will not work on spells that require the enemy to roll a saving throw.

Quote from Emmber >>

Yes it will apply to spells that have an attack roll. It will not work on spells that require the enemy to roll a saving throw.

Not only is this true, but you probably would not want to add a bonus to an enemy’s saving throw even if you could.