They are concerned that these Jewish "extremists" plan to build their own structure on top of the Mount, even though - they say - there is no historical evidence that there was any Jewish Temple on the site.
The League said that Jewish visits to the site were "gravely dangerous."
Immediately afterwards, the League also condemned Israel's practice of limiting access to the Mount for Palestinian Arabs who are under 40 years old. It says that such limitations are "contrary to international law and the right of citizens to worship anywhere, and the occupying power may not violate the freedom of worship guaranteed in the Charter of the United Nations."
The Arab League suddenly fervently believes in freedom to worship - right after saying that Jews have no rights to worship on the Temple Mount!
Hypocrisy in the Arab world is not hard to find, but to see such blatant hypocrisy within the same statement is a bit more notable.
By the way, the UN's International Covenant on Civil and Political Rights has this to say about freedom to worship, in Article 18, paragraph 3:
Freedom to manifest one's religion or beliefs may be subject only to such limitations as are prescribed by law and are necessary to protect public safety, order, health, or morals or the fundamental rights and freedoms of others.So the League is lying yet again - Israel is perfectly within its rights under international law to restrict who can visit the Temple Mount to avoid violence and to ensure reasonably free access to all religions - a goal that the Arab League explicitly does not believe in.