The American world number two is the highest-ranked golfer left in the field after number one Jason Day withdrew on Tuesday, citing concerns over Zika, a mosquito-borne virus that the World Health Organisation says is spreading rapidly in the Americas.
“Right now, I’m uncertain,” Spieth told reporters ahead of the WGC-Bridgestone Invitational.
“I have not received enough information to make an informed decision either way or not so as we gather more information I will be able to make a decision one way or the other.
“When I feel confident, I will make a decision either side.”
Golf is returning to the Olympics for the first time since 1904, but the Games have already been hit by several high-profile withdrawals.
Ireland’s Shane Lowry, the world number 25, also withdrew on Tuesday, saying his decision was based on firm medical advice.
