Does this mean to break an agreement?

Not, it mean take an agreement.

Why don't you provide us with more context?

Here's the context: http://www.elpais.com/articulo/espana/Zapatero/acuerda/Vaticano/abrir/etapa/dialogo/colaboracion/respeto/elpepuesp/20090204elpepunac_7/Tes

Yes, poli you touch an agreement with the government, I feel that the context is easier if you have understood the idea, you need to know, for example, I wanna say, I'm agree with take an agreement with my wife in our divorce, jajajaj, it does not mean, I'm divorcing me of my wife, only I gave a simple example.

In this case, I think they are promising not to touch/bring up/discuss/mention/change their agreements with the Vatican in light of the new Freedom of Religion law.

"El Gobierno garantiza al Vaticano que no tocará los acuerdos de la Santa Sede. "
The Goverment guarantee the Vatican that the (current) accords (with the Vatican) will not be touched.

Socialist goverment of Spain is doing things that the Vatican does not like (gay weddings, more freedom to abort). It could be that the Goverment can like to change the accords, due to this fatcs.
But the Goverment is now assuring this will not affect the current accords with the Vatican.

Saludos :D

Thanks guys. That's what I thought. It means not to break (previous) agreements (in other words: standard political diplomacy)

Not only break. It's really "touch". Perhaps you do not break the agreements, but you change some things slightly (Less much money to be given, control the number of people allowed, more import taxes..) "No tocará" means really "Not touch". To break, is "romper acuerdos".
Saludos :D

I think I would translate it literally into English as touch or possible change/modify.

<<[...]De la Vega también [...] le ha garantizado que "en ningún momento se van a tocar los acuerdos con la Santa Sede".>>

The expression "no tocar los acuerdos" means that those agreements that have been previously established will not be renegotiated: they won't be submitted to any change and they won't even be subject to discussion.