The pair, in a letter to Schulz, congratulated the German on his election success - over the weekend - as Europe's official Socialist party candidate for the post of president of the European commission.
However, Cohn-Bendit and Harms, the co-presidents of parliament's Greens/EFA grouping, also called for Schulz to step aside from his official parliamentary duties in the run up to the European elections in May.
"The forthcoming European elections and decision on the commission president will be an unprecedented and significant development for the democratic functioning of the EU" - Daniel Cohn-Bendit and Rebecca Harms
The two deputies said that a 'clear distinction' should be drawn between the role of European parliament president and the upcoming campaign for the presidency of the European commission.
"The forthcoming European elections and decision on the commission president will be an unprecedented and significant development for the democratic functioning of the EU," say Cohn-Bendit and Harms in a press release issued on Monday.
"This will be a challenging period for all candidates nominated by the European political families, as they will need to mobilise citizens for the elections and offer them distinct political choices for the future of the EU."
"Against this background, the Greens believe a clear distinction must be drawn between the non-political and representative function of the president of the European parliament and the campaign for the presidency of the European commission."
"There should be no confusion between the role of the parliament's president in representing EU citizens, as chair of the only democratically-elected institution, and the political nature of the decision on the presidency of the European commission.
"We are therefore calling on Martin Schulz to draw a distinction between the two roles by stepping aside until the end of the mandate and passing his functions over to the vice-presidents of the European parliament in order to avoid any conflict of interest and ensure impartiality."
"I don't understand why there should always be exceptions for Schulz. When commissioners run for the parliament, they also have to stand down from their posts" - Herbert Reul
The Greens/EFA group call was backed by EPP deputy Herbert Reul, who also called for Schulz to stand down, arguing that his fellow German had "already done enough campaigning on the back of the European parliament in order to become commission president".
"I don't understand why there should always be exceptions for Schulz. When commissioners run for the parliament, they also have to stand down from their posts," added Reul."
"As president of the European parliament and the official candidate of the Socialists for the post of commission president, Martin Schulz is in the same position. This is why the same yardstick should apply to him."
Meanwhile, the EPP themselves are set to go into their pre-election 'congress' this week in Dublin with three contenders for the post of commission president candidate, after Michel Barnier threw his hat into the ring on Friday.
The Frenchman, currently European internal market commissioner, joins former Luxembourg prime minister and frontrunner, Jean-Claude Juncker and former Latvian prime minister Valdis Dombrovskis in a three-way race for the EPP nomination, which will be announced towards the end of the Dublin congress on Friday 7 March.