I am searching for a hyperparameter tune package for code written directly in Tensorflow (not Keras or Tflearn). Could you make some suggestion?
Usually you don't need to have your hyperparameter optimisation logic coupled with the optimised model (unless your hyperparemeter optimisation logic is specific to the kind of model that you are training, in which case you would need to tell us a bit more). There are several tools and packages available for the task. Here is a good paper on the topic, and here is a more practical blog post with examples.
Out of these, I have only really (that is, with a real problem) used hyperopt with TensorFlow, and it didn't took too much effort. The API is a bit weird at some points and the documentation is not terribly thorough, but it does work and seems to be under active development, with more optimization algorithms and adaptations (e.g. specifically for neural networks) possibly coming. However, as suggested in the previously linked blog post, Scikit-Optimize is probably as good, and SigOpt looks quite easy to use if it fits you.