The European Union has its currency controlled by the European Central bank whose job it is to identify risks to the Euro and deal with those potential risks. Some policymakers in the United States define controlling inflation or intervening with currency in spite of the market to maintain financial stability or having a central bank weaken its own currency as being currency manipulation. Mario Draghi of the European Central Bank does not see this as currency manipulation and sees applying cuts to the interest rates and/or value of the Euro as fulfilling the mandate of the European Central Bank, not currency manipulation. When President Trump accused the European Union of currency manipulation, Mr. Draghi responded by saying:
We have our remit, we have our mandate . . . defined as [targeting] a rate of inflation close but below 2 per cent over the medium term.
I just said a moment ago we are ready to use all the instruments that are necessary to fulfil this mandate and we can’t target the exchange rate.
Basically, the United States doesn't currently have a strong definition for what currency manipulation is. What one policymaker views as currency manipulation can be viewed by someone else as simple 'balancing of the budget'. Mario Draghi and the bank of the European Union admit to engaging in actions that would, according to the definition of currency manipulation by some US policymakers, count as trying to get an unfair economic advantage such as “further cuts in policy interest rates". To the European Union, however, this is less unfair manipulation and more 'what they should do to maintain the economic stability of the European Union'. As far as I know, the European Union has no official definition for currency manipulation and not all policymakers would see this as currency manipulation.
While there is no central definition, The Economist uses an unofficial standard for judging which nation is most liable for currency manipulation as show in the following graph:
As you can see with this graph, Germany is generally on the low-end when it comes to currency manipulation with Taiwan and Switzerland being generally more manipulative of its economic assets. So even by the standards of The Economist, Germany has not really engaged in currency manipulation.