Late in making restaurant reservations for June 10-15 Paris Tour

Is this a Rick Steves tour? Are you staying in the 7th? If so, check out Café Roussillon, on the corner of Grenelle and Rue Cler. We've been able to get in there without reservations.

I don't think we ever were in the situation of not finding some place to eat. There will be bistros, cafés, all around. We never made a reservation for lunch, and seldom for dinner.

You must have selected some very famous / hip places to run into this problem more than 1 month before your trip. Most restaurants in Paris don't need that much anticipation: look at, for example, Michelin Restaurants (Guide Michelin, English website available), David Lebovitz recs (great blog), or even Google Maps (you'll always have to cross-check but anything 4.5+ is probably excellent in its category), within 1/2 mile from your hotel, and you should get plenty of options. Online booking is increasingly common, too.

I second dining at Café Roussillon, on the corner of Grenelle and Rue Cler. in the 7th. Just dined there a number of times in the last week . All the restaurants in that area are great and you shouldn’t need reservations .

Depending on where you are, the Cafe Breizh restaurants are good and shouldn't need reservations for lunch. I don't even know if they take them. They probably do for dinner. We just went to the one near Musee Cluny, but there are others. Very good food and good prices. Try googling them. There are so many places to eat in Paris, and I would guess 90% are good, so you will eat well wherever you end up. (Caveat...in the streets in the Latin Quarter there are several with very lackluster prix fixe meals. Hawkers outside them will try to convince you to dine at them. We have always been disappointed with them.)
Bon appetit!

Try Auberge Bressane on the ave. de la Motte Piquet. You def need reservations, but you'll have a nice meal.

Can you tell us where you’re going to be? I’m sure we can provide suggestions for a lot of different areas.

Thank you everyone for your suggestions. I feel better now that there should be restaurants where you do not need reservations. I will try the ones mentioned.

We are staying near the Eiffel Tower and visiting the Louvre on Wednesday. We'll try Cafe La Roissillion as it was mentioned more than once.

David Lebovitz and Paris by Mouth are wonderful sources for me for Paris restaurant recommendations. Last September we had an excellent dinner at Le P'tit Troquet which is very close to the Eiffel Tower. Les Antiquaires in the 7e has been consistently good. La Terrasse du 7ᵉ was recommended by Rick Steves and for good reason--we've had both lunch and dinner there on separate vacations. Bistrot L'Estrapade in the 5e was wonderful (and close to Emily in Paris locations that I had to see!) We had reservations for all the restaurants and all had outdoor seating which was very important since it was 95-96 degrees and much hotter inside the restaurants.

Thank you for your suggestions!