"We are very focused on profit and profitability, with a low cost iron ore business. We have cash cost of $17 if you take into account the current spot prices in energy prices, and a sales price of $62 a ton—$17 to $62—that is a pretty good margin by anybody's book," Walsh said on "Squawk Box."
"Yes we look at build versus buy, every business does, but right now is not the time to go out and buying distressed assets, distressed high cost assets. More importantly we are focusing n the very significant growth options we have for organic growth," he said.
Earlier Thursday, the group announced a $2 billion buyback, despite reporting its worst half-year profit in two years, and raised its annual dividend to shareholders by 12 percent, beating forecasts.
The miner managed to force through major cost cutting measures in the last year, slashing net debt to $12.5 billion, way beyond analyst expectations, as it posted a 78 percent increase in full year profit for 2014 to $6.5 billion, up from $3.6 billion in 2013.
Investors cheered the results, with shares in the group rallying over 3 percent in London trading. (Click here for the latest price.)
Read MoreWhy iron ore won't rebound any time soon
Rio Tinto continues to struggle with a sharp fall in the price of its main commodity, iron ore, which has fallen from its peak of nearly $200 a ton in 2011 to around $62 this year.
Walsh said the group had "surprised the market" with its results and that options for future buybacks "bode well" as the company is "strongly committed to shareholder returns."
"We actually need to see how 2015 is going to pan out. We have taken early action this year to reduce our debt further, to improve our capital, to improve our operating costs. We are working on the basis that this will position the business well for the future," he added.