If the conditions are not met and the Greek reform plans presented to creditors this week are not substantiated with figures, no more money will be paid, Schäuble said on SWR public radio, stressing that the commitments Athens agreed with creditors the EU, ECB and IMF remain valid.
"If they fulfil those, then they can still receive the outstanding payments. And if they don't fulfil those, there will be no payments," he said.
Schäuble added that "not a single euro will be paid before then".
MPs from Chancellor Angela Merkel's Christian Democratic Union (CDU) and their allies the Christian Social Union (CSU) will meet on Thursday morning for a “test vote” to gauge the mood of the party.
There will then be a binding vote in the Bundestag (German parliament) chamber on Friday.
Greece's new left-wing government has secured the four-month extension to its lifeline bailout programme with promises of ambitious reforms and a pledge to stick to its financial commitments.
The breathing space beyond a Saturday deadline - assuming parliaments across Europe vote in favour - prevents the immediate worst-case scenario of national bankruptcy, a run on banks and even a chaotic exit from the eurozone.
Without agreement from the Bundestag and other European parliaments, the extension of financial aid to Greece cannot go ahead.
Merkel on Wednesday welcomed as a "starting point for discussions" reform pledges made by Greece in return for the extension.
"This is good news considering what was being said only weeks ago," Merkel said, adding however that "much work lies ahead" in talks between Athens and its international creditors..
Eurozone finance ministers called the pledges a "starting point", the ECB pointed out that they "differ from existing programme commitments in a number of areas", and IMF chief Christine Lagarde said the list lacks "clear assurances" on previous reform promises.
Schäuble began his campaign on Tuesday night, briefing the leaders of the governing CDU-Social Democratic Party (SPD) coalition in Angela Merkel's office.
Although the coalition has an 80 percent majority in the chamber, there are already fears that some CDU and CSU MPs may vote against the deal.
CDU foreign policy specialist Wolfgang Bosbach said at a party gathering on Tuesday that he would not vote for the extension of aid to Greece.
Should all the parliaments agree to the extended bailout, Greece will have until April to present details plans for economic and administrative reforms.