Eurogroup chief Jeroen Dijsselbloem said Greece must accept the rules of the eurozone if it wants to stay in the currency bloc, a German magazine quoted him as saying on Friday.
Leftist party SYRIZA, which leads in the polls ahead of Sunday's Greek election, says it wants to remain in the single currency but also pledges to end the austerity imposed under the country's international bailout.
Dijsselbloem pointed out in an interview with Spiegel online that all the leading politicians in Greece have said they want to keep the euro.
"If you say that, then that means you have to accept the rules and agreements," he said. "And that also means: any country that need support to finance its economy and public expenditures must stick to those conditions."
Dijsselbloem added that it will not work if a country "simply asks for loans without meeting any sort of conditions."
He also said every Greek government will depend on further support from eurozone countries.
Syriza leader Alexis Tsipras told a rally in Athens that an end to Greece's "national humiliation" was near after opinion polls showed his party pulling ahead.
Tsipras urged Greeks to give SYRIZA an outright victory in Sunday's vote so the country could turn its back on four years of austerity under the terms of the EU/IMF bailout.
The election is being closely watched by financial markets who fear a SYRIZA victory could lead to a stand-off with European Union and International Monetary Fund lenders and push the country close to bankruptcy or an exit from the eurozone.