Since the Pledge of Allegiance is meant as a very brief (31 words) general statement of support for the flag and the country as a whole, it says very little about any specific freedom like the freedom of speech.
The only mention of anything that is very closely connected to freedom of speech comes at the end of the Pledge. This is in the words "with liberty and justice for all." When we say that all people in the US have "liberty" we are surely referring (among other things) to the freedom of speech. Most people would place this particular freedom very high on the list when asked what "liberty" means.
However, we should not infer from this that the Pledge is anti-free speech. Instead, it is a very short statement that could not possibly list even the most important sorts of liberties we have and the ways in which justice is provided for us.