"Ponting has reprimanded Martyn for making a gesture filmed by media when the Australian team was outside its Melbourne hotel (on Friday)," CA said in a statement. Martyn was filmed raising his middle finger towards a cameraman.
The Western Australian World Cup winner was facing pressure in Friday's match against Zimbabwe in Melbourne to retain his place in the side after scoring just 78 runs in his first six innings of the triangular series.
The right-hander went on to blast eight boundaries and dominated an opening stand of 59 with Matthew Hayden, scoring 42 from 40 balls.
Ponting said: "I acknowledge he didn't mean to cause offence but his action was inappropriate and not fitting of an Australian player and ambassador for the game."
Ponting took the decision to reprimand Martyn, 32, under the players' Spirit of Cricket code, CA said.
"Damien Martyn has apologised for his action, which he agreed was foolish," CA said.
Martyn said: "I am sorry for the offence caused by the gesture and apologise to the public who have seen it on TV. My action was in no way pre-meditated, nor did I mean for it to cause any harm."
No further action will be taken by CA, who have tried to counteract negative publicity about the team's on-field behaviour in recent years by launching the Spirit of Australia code amid much fanfare in October 2003.
CA, the national ruling body, issued a statement in October warning Australia's players they faced life bans for on-field sledging as part of the new code.
