It will depend on the situation and what is meant, as this sentence is not usually said on its own. It is usually followed with another clause. There are at least two ways to take this sentence. Forward here could mean "pushy", or "cocky" or "presumptuous" or "assuming". So we could restate it as "I don't mean to assume,(but)..." or "I don't mean to be pushy", or "I don't mean to pry". The other way its used is in a romantic context:"I don't mean to be forward, but would you like to go to a movie with me sometime?" It's often meant to pay someone a complement without making them think you have a romantic interest - yet it can also imply romantic interest. "I don't mean to be forward, but you have beautiful eyes." To restate it in this context you might say: "Don't take this the wrong way, but you have beautiful eyes".

I'm sorry if I am being presumptuous. Please excuse me if I am being too brash.

"I don't want to sound too forward." "I don't mean to sound brash." "I don't mean to sound conceited." These are a few examples of how you could say it. However, the first example is the most commonly used phrased.

You could also say "Sorry if I am being too forward."

I think you could also say "I don't mean to sound so bold." or "I don't mean to sound so pushy." also.