The body said it has found the new regulations to be skewed after a week's consultation with the country's sports ministry and Olympic committee.
The International Association of Athletics Federations (IAAF) last week confirmed new rules which effectively give Semenya a choice of taking the medication to restrict her testosterone or move to longer distance events.
"As a member federation, we will engage the IAAF as our mother body and if they do not change their minds on this new rule after this engagement, we will proceed to the Court of Arbitration for Sport (CAS) for further assistance on the matter," ASA said in a statement.
But it gave no details on what grounds it would seek to set aside the new rules, which come into effect on Nov. 1 and will likely most effect Semenya.
"ASA once again takes the opportunity to re-affirm our support for all our athletes who may be affected by this new ruling," the statement added.
The rules seek to prevent women with hyperandrogenism, which produces higher than normal levels of testosterone and is deemed by the governing body to give them an unfair advantage, from running distances from 400m to the mile.
They would only be allowed to compete at international level if they took medication to reduce naturally occurring levels of testosterone.
Semenya, a double Olympic and triple world champion over 800m and who completed the 800-1500 double at the Commonwealth Games last month, has always been a controversial figure in the sport as its authorities have sought a solution that respected her rights while also providing a 'level playing field'.
The 27-year-old's powerful physique and deep voice, categorised by the IAAF as athletes with a Difference of Sexual Development, left some rivals complaining they faced an impossible and unfair challenge.
The IAAF had similar regulations in place for four years but they fell foul of a ruling in 2015 following an appeal on behalf of Indian athlete Dutee Chand, who had been banned from competing because of her testosterone levels.
REVIEW OF EVIDENCE
The IAAF Council said earlier this year it had completed a review of available evidence after the CAS ruling had instructed them to do so.
The South African began raising eyebrows when she won the world junior championships in 2008 and the senior world title the following year, with dramatic improvement in her timings.
The IAAF made Semenya take a sexual verification test, which was initially kept secret but revealed by the media in 2009.
Since then virtually all of Semenya's performances have been followed by questions about her sexual and physical status, but she has long stopped answering them.
(Additional reporting by Mitch Phillips; editing by Sudipto Ganguly)
