That's very young to leave it's mother.Have you tried putting the puppy in a crate and let your other one just sit beside her.I'm sure it's just excitement as he's only young himself,is he neutered ? If not and she's female could be why ?
That is an awfully young pup to be bringing home...I don't know if the age of the pup could have anything to do with the older dog's reaction or not, but I'd be very watchful of the two of them together.
I like Michele's idea of crating the pup until the older dog gets over himself!
I rescued Jazz at 11 weeks. Tango was 2 something at the time. He behaved towards Jazz a lot like you are describing. He was feeling playful and wanted to entice Jazz to play with him. He still behaves that same way towards her when he wants to play