BRUSSELS (Reuters) - German Chancellor Angela Merkel urged Greek Prime Minister Alexis Tsipras on Friday to accept a "generous" offer from his country's creditors, saying it was now up to Athens to take a step in the direction of its euro zone partners. "We have taken a step towards Greece," Merkel said at a news conference in Brussels. "Now it is up to the Greek side to take a similar step." (Writing by Noah Barkin and Paul Carrel)