Commentary for Sanhedrin 118:31

s.v. "And behold, Fructification and Muliplication": It is astonishing -- why do you think it was not said to gentiles? And if it is because it was not counted in the Seven Noahide Laws -- behold v.s. [Sanhedrin 58b] "rise-and-do laws are not counted." And possibly this is also an abide-and-refrain, because He who commanded Fructification and Multiplication also commanded not to waste semen.