Schulz told Germany's Welt am Sonntag newspaper that he had counselled Alex Tsipras against lambasting Chancellor Angela Merkel and her government when he met the Greek Prime Minister on Thursday for talks on renegotiating Greece's massive bailout.
"I emphatically recommended to him to verbally disarm. That brings him nothing," said Schulz, a German.
"Tsipras is well advised to end his attacks on Angela Merkel.
He pointed out that in the end it would be the German government, among others, that would have to help him.
Germany has reiterated that it expects Athens to stick to its commitments for fiscal and economic reform, made as part of the bailout package, since last Sunday's election that brought the radical anti-austerity party Syriza to power. Germany has shouldered the bulk of Greece's loans, and Merkel said Saturday that she did not envisage fresh debt relief for Greece.
"There has already been voluntary debt forgiveness by private creditors, banks have already slashed billions from Greece's debt," she told the Hamburger Abendblatt daily.
The European Parliament president, who was the first EU leader received by Tsipras, said it was not just the Germans but the whole European Union that was eyeing developments in Athens sceptically.
"It may perhaps go down well with some to pummel the Germans but it is also shortsighted and doesn't take us further forward," Schulz said.