If you want to load pre-trained weights that include convolutions (layers Convolution2D or Convolution1D), be mindful of this: Theano and TensorFlow implement convolution in different ways (TensorFlow actually implements correlation, much like Caffe), and thus, convolution kernels trained with Theano (resp. TensorFlow) need to be converted before being with TensorFlow (resp. Theano). Here's how.
From Theano to TensorFlow
Keras backend should be TensorFlow in this case.
First, load the Theano-trained weights into your TensorFlow model:
Then, iterate over the weights and collect conversion ops: