The Vertical reported that Gasol, who will turn 37 in July, may enter talks to return to the Spurs at a lower salary to help the team entering free agency.
In addition, the San Antonio Express-News reported that David Lee also is expected to opt out of his $1.6 million deal with the Spurs for next season.
Spurs coach Gregg Popovich mentioned that the club's decision-making process in free agency would be "pretty complicated" and depend "on a lot of factors." Gasol's decision serves as one of the most significant components in shaping San Antonio's plans for free agency.
During a 2016 offseason in which the Spurs (along with most of the league) chased Kevin Durant, Gasol emerged as the club's most high-profile acquisition in free agency.
The veteran finished his first season in San Antonio averaging a career-low 12.4 points, but he also attempted a career-low 9.4 shots per game. Gasol averaged 7.8 rebounds and connected on 53.8 percent from 3-point range.
Popovich said Gasol adjusted to San Antonio's system "better than most people who have come here for the first year. It's a whole new system, all new players, many of whom are getting used to the system at the same time he is. So, it's not like it was our core group and just added him. Considering all that, I think he's done a great job of trying to figure things out; accepting coming off the bench to make us a better team. I think he did a good job."
Gasol fractured the fourth metacarpal on his left hand in January and eventually lost his starting job to journeyman Dewayne Dedmon. Still, Gasol embraced the new role and transformed himself into somewhat of a stretch-5 to better fit his new responsibilities off the bench.
Set to enter his 18th NBA season, Gasol has averaged 17.9 points and 9.4 rebounds for his career.
ESPN's Michael C. Wright contributed to this report.