Is it possible to trade instruments like "EUR/USD" on options? There is a options broker offering some API with smaller requirements than IB?

To answer your two questions:

1) Did you mean options on forex? The closest thing I can find is futures options. On the CME, for example, you can trade options on currency futures. There might also be currency ETF's with options.

2) "Smaller requirements"? Did you mean initial balance, initial margin, or maintenance margin?