"We want to keep Britain in the EU and not force it out," Schäuble told the weekly Frankfurter Allgemeine Sonntagszeitung. "But I will also say that does not mean anyone can blackmail us."
Asked whether a debate raging in Britain about a possible referendum on the country's future in the 27-member bloc was "dangerous", Schäuble said the European Union needed to send a clear message to the rest of the world.
"Our British friends are not dangerous. But a referendum would create uncertainty," he said.
He said he only got "cross" with Britons over football, adding he hoped for "more British engagement in Europe, not less."
Britain has belonged to the European Union since 1973 but has not joined the 17-nation eurozone.
Schäuble has served as Chancellor Angela Merkel's main ally in Berlin in plotting an austerity-driven course to resolve the eurozone debt crisis as well as greater political integration of the bloc.
British Prime Minister David Cameron, a Conservative, said last month he still supported British membership of the EU but could not accept the "status quo" and called for a "new settlement" involving the repatriatiion of some powers. He has so far avoided offering a clear "in-out" referendum despite strong pressure for clarity on the issue from his party.
Tensions flared last month when Cameron opposed a new €1 trillion EU budget for the next seven years, saying that it was unacceptable to raise spending at a time when many countries were implementing austerity measures at home.
A recent poll in British weekly newspaper The Observer found that 56 percent of Britons surveyed would vote to leave the EU given the chance.