Macの場合であれば~/.bash_profileに以下の一行を追加でOKです。
export TF_CPP_MIN_LOG_LEVEL=2
Pythonスクリプトに以下のコードを埋め込んでもOKです。
import os
os.environ['TF_CPP_MIN_LOG_LEVEL'] = '2'
TensorFlow（v1.1.0）を立ち上げるたびに以下のようなワーニングが出てきて目が潰れそうになってましたが、この方法でなんとかなりましたとさ。
2017-06-14 10:09:04.651948: W tensorflow/core/platform/cpu_feature_guard.cc:45] The TensorFlow library wasn't compiled to use SSE4.1 instructions, but these are available on your machine and could speed up CPU computations.
2017-06-14 10:09:04.651968: W tensorflow/core/platform/cpu_feature_guard.cc:45] The TensorFlow library wasn't compiled to use SSE4.2 instructions, but these are available on your machine and could speed up CPU computations.
2017-06-14 10:09:04.651972: W tensorflow/core/platform/cpu_feature_guard.cc:45] The TensorFlow library wasn't compiled to use AVX instructions, but these are available on your machine and could speed up CPU computations.
2017-06-14 10:09:04.651976: W tensorflow/core/platform/cpu_feature_guard.cc:45] The TensorFlow library wasn't compiled to use AVX2 instructions, but these are available on your machine and could speed up CPU computations.
2017-06-14 10:09:04.651979: W tensorflow/core/platform/cpu_feature_guard.cc:45] The TensorFlow library wasn't compiled to use FMA instructions, but these are available on your machine and could speed up CPU computations.