Modise, who has 57 caps, says he is not retiring, but feels this is the right time for coach Gordon Igesund to bring in new blood to the Bafana set-up.
"I'm not feeling sad or anything. Honestly, this time in my career was going to come anyway," he tells KickOff.com.
"The national team is not a club; they select players according to their performances for their teams and I don't think I'm performing to that standard.
"Honestly, I think it is high time that there are new faces in the Bafana set-up. I've been there over five years and I think I've done what I could. It is time for new guys to take the team forward. I'm not going to be bitter about not being selected to the national team."
The 29-year-old says he is glad that he didn't go to Brazil as he and his Sundowns teammates are trying to help find a solution on what is happening at the club with their poor recent results.
"I'm glad I didn't go so that I'm here to try and fix what's happening within the team. This is where I enjoy being at most; not that I don't enjoy being with Bafana, but this is where I get paid.
"I just want to focus on the team and help them do well; Bafana is the last thing on my mind.
"I'm wishing the guys the best of luck, but I think it's high time that the new faces come into the Bafana set-up. I've been there for a long time, it's my time now to focus on my club," he says.
"I need to prioritise, age is not on my side. I think I achieved what I wanted to as a footballer. I played in the Africa Cup of Nations before; I played in World Cup and Confederations Cup, I have played in all the big tournaments, there is nothing for me to play for anymore with Bafana.
"I'm not retiring; my focus is on my team. If I'm called-up I will go and play for Bafana, but now I just want to play for Sundowns and win something with Sundowns - that's my biggest goal this year and I'm going to do it," he says.