All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.
Eating in the mentioned restaurants is permissible, but make sure that the meat is lawful; i.e., fulfils the following two conditions:
A: The meat should be permissible in Islam.
B: It should be slaughtered according to the legal way and it should not be killed. Try not to use any thing in which impurity may be suspected, either be it in a Muslim’s restaurant or in a non-Muslim’s restaurant.
For more benefit on meat of animals slaughtered by the People of the Book, please refer to Fataawa 82323, 82065, 81234, 393961, 330952, 82899, and 84072.
Allah knows best.