From what I understood, before you aspire to reach a spiritual level, you must to rise to a virtuous plan, but then why did Krishna encourage Arjuna to be in a state of passion and fight? And is this passion natural of a warrior or is this the same passion that binds us to the fruits of our actions?

Krishna consciousness leads to virtue, as much as virtue leads to Krishna consciousness. In my own life, I became virtuous when I discovered Krishna. Krishna told Arjuna that he must do his duty. As a great warrior, Arjuna already had the passion to fight. Krishna did not create Arjuna’s passion.

Also, we have to remember the historical context. Arjuna wanted to fight not merely from passion, but rather to restore constitution government and justice in the world. It was a noble fight to protect the world.