[Greek PM Tsipras welcomes European Council President Tusk at the Maximos Mansion in Athens]ATHENS (Reuters) - Excluding Greece from the passport-free Schengen area will not solve Europe's migrant problem, EU Council President Donald Tusk said on Tuesday, but acknowledged the crisis was testing European cohesion to its limits. "For all those talking of excluding Greece from Schengen, thinking this is a solution to the migration crisis, I say no, it is not. "Let me be clear, excluding Greece from Schengen solves none of our problems," Tusk told reporters after meeting Prime Minister Alexis Tsipras in Athens. (Reporting By Renee Maltezou, writing by Michele Kambas)