The 32-year-old, who has earned 125 caps and won three major honours with the national team, is currently on holiday following Spain's exit from the World Cup to Russia in the last 16.
The Manchester City man told The Mirror that he wants to devote more time to seven-month-old son Mateo, which could mean a departure from the international scene.
"Since the World Cup I have been concentrating 100% on my son. I'm returning to Manchester on Sunday and then I will start thinking about football again," the midfielder said. "I honestly don't know whether I will continue playing for Spain.
"It is something I must decide in the coming days and weeks and when I go back to Manchester. At this moment, the only things on my mind are my son, my girlfriend and my family."
"I will talk to other people, maybe I will talk to [City boss] Pep [Guardiola], but in the end it will be only my decision."
Silva made his international debut against Romania in 2006.