A number of clubs were said to be interested in the Armenian during the summer, including Liverpool and Tottenham Hotspur, but the 24-year-old opted for the Bundesliga outfit.
"I had many options, but I decided on Dortmund because I like the type of football that is played here," he told German newspaper Die Welt.
"Since we played with Shakhtar in the Champions League against BVB, I've watched all Dortmund games on TV. BVB has not only played fantastic football, but also a football that suits me. I thought: 'This is a team where I can grow, can develop'.
"Money is not so important in football. There's only room for football. I live football, think football, feel football, and if I play well, the money comes anyway. I have come to Dortmund to play and not to sit on the bench, as might initially have been the case in England."