"Eu rezerv o masă bună pentru cină."
Translation:I book a good table for dinner.
I don't believe anyone would use this sentence in the present tense. If we are in the act of reserving, there would be an auxilliary verb, such as "I would like to....[reserve...]." Generally, we'd use the past tense here.... and of the options presented, the imperfect was the closest (although i would prefer the compound past to the imperfect....)
The present tense can be used in Romanian to describe past actions, why not? It's a sort of literary style, called " prezent narativ ".