Speaking on ARD television's Bericht aus Berlin program, Merkel said that "a classic haircut of 30, 40 per cent of debt cannot happen in a currency union."
But Merkel, who persuaded German lawmakers on Friday to give their overwhelming backing to another financial rescue package, suggested that she was open to discussing ways to lessen the burden on Athens.
She said, for example, Greece previously has been given more favorable interest rates, time extensions and other relief
Though the broad outlines of the Greek bailout were agreed last Monday by the eurozone's 19 leaders, the details are now being negotiated.
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The discussions, which are expected to last four weeks, will include economic targets and reforms deemed necessary in return for an anticipated 85 billion euros ($93 billion) over three years.
Merkel pushed for them to move as quickly as possible, saying that it was important that "the country gets back on both feet quickly."
"The option was discussed but we decided on this option, which was quite apparently the right one for all the other" eurozone nations, she said.
Talking to Parliament on Friday, Merkel said the alternative to the new rescue package "would not be a time-out from the euro that would be orderly ... But predictable chaos."
German Vice Chancellor Sigmar Gabriel, who is also economy minister and chairman of Merkel's junior coalition partner, the Social Democrats, on Sunday criticised Schaeuble for bringing up the idea of a timeout, saying "it wasn't prudent to make this suggestion as a German suggestion."
Merkel skirted the issue when asked about internal strife, saying only that her coalition and her party would work together going ahead, and that "the finance minister will conduct the negotiations the same way I will.