Ferrari didn't veto anything.

The FIA (Max Mosely in fact) disallowed the proposed track changes.

Changing tyres would be going against 5 new 2005 rules which have restricted Ferrari somewhat this season anyway.

Michelin were given the option to run with penalties imposed, but they refused.

Ferrarri did nothing wrong. It was Michelin and the FIA who caused the problem and couldn't resolve it respectively.