Have a higher combat level? I'm not sure what you mean. The only limitation on Tremere's ability in combat is that their phyiscal stats are capped at (4) and that physical abilities are not their primary requisite in character creation. Quite frankly, they can still use "blood buff" in combat (which,I believe, boosts their physical attributes to 5 anyway...), which negates most of these limitation(s) for more melee inclined players.
Regardless, you can probably by-pass the limitation using cheats. The complete list can be found
here . You can add attribute points to your character. My guess - though I've never tried - is that you probably can add a fifth level in an attribute that way, as well. Though, personally, since you have access to blood buff anyway, I wouldn't be too concerned about maximizing your physical attributes.
When playing a Tremere, I'd add, your bread and butter is not going to be physical statistics. You're better off focusing on dominate and thaumaturgy. Those are both very potent disciplines when used correctly.