BERLIN (Reuters) - German Chancellor Angela Merkel said on Monday there was no wiggle room to lower interest rates for Greece, but euro zone partners could push back the date when Athens has to start paying back its bailout credits. "I think when it comes to interest rates, we have no room for manoeuvre because the rates are already very low," Merkel said during a news conference in Berlin. However, she also said that there was some wiggle room regarding the so-called "grace period", meaning when and how much Greece should pay back. (Reporting by Michael Nienaber; Editing by Caroline Copley)