Absolutely. The government has a right to issue permits restricting where and when groups can organize as long as they don't discriminate based on the content or beliefs of the organization. In other words, they can restrict speech on the basis of time and space available.
Also, you don't have free speech in high-traffic buildings (such as inside classrooms/buildings, even in a public school). You can cause a fire hazard if you're blocking an entrance, and, if people are required to be in that building (say, if they're going to class), they're considered a captive audience, and they shouldn't have to listen to someone making a statement.
Your freedom of speech ends where my freedoms begin. The government can restrict speech if it imposes on someone else's basic human rights. That's a bit of a grey area, but sometimes protecting people from personal attacks is more important than protecting the right to make them. Not always though, because sometimes the restrictions go too far, and we don't say anything for fear of "insulting" another person or group.