Translation:The president was against the teachers' strike.
Hi, while "the strike of the teachers" is not literally incorrect, it would be very unusual and not natural English. We always say "the teachers' strike", "the miners' strike" etc. Even if we wanted to emphasise eg that it was the teachers who were on strike rather than, say, the taxi drivers, we'd do it simply by putting the stress on the word itself "it was a teachers' strike, not a taxi drivers' strike". (I'm a native speaker of British English.)