Villa is his country's record goalscorer and looks set to have capped his Spain career with a goal, having scored the opener in Monday's final FIFA World Cup group game against Australia.
That was his 59th strike from 97 caps and the 32-year-old cut an emotional figure as he watched the remainder of the match from the bench after being substituted in the second half.
Villa completed a move from Atletico Madrid to New York City in the MLS recently and will spend a brief period with A-League outfit Melbourne City to maintain match fitness ahead of the franchise's debut campaign.
However, he warned of a need for realism around whether he can continue to play on, with the former Barcelona man strongly hinting he could opt for retirement.
"I've always said that I love the national side and I've always dreamed about them," he told the Spanish press.
"I'd play until I'm 55 but it is impossible and you have to be realistic. I've taken the decision to go to the MLS and I'll not compete for a few months, which makes it difficult to carry on.
"Then, after these six months, we'll see. If the boss wants me back, brilliant, but it's difficult and we have to be realistic."
Defending champions Spain exited the tournament in Brazil at the group stage following defeats to the Netherlands and Chile, with the 3-0 win over Australia offering scant consolation.
