Mrs May said the Government was also looking at new orders to ban radical groups, including new civil powers to target individual extremists.
In a written ministerial statement, she said there were plans to give the Charity Commission greater powers after an extremist task force was set up to look at ways of stopping the spread of radical hate-preaching.
The task force was announced following Lee Rigby's death.
She said the Government was also working with leading internet companies to restrict terrorist material online and make it easier for the public to report extremist content.
In her statement, Mrs May said the task force met for the last time on November 26.
She said: "During the last five months, the task force has considered a range of measures to confront extremism in all its forms, including in communities, schools, prisons, faith institutions or universities."