Along the same lines, but a little different.
If Roth planned to have Mike killed in Cuba, he would take over Mike's operation in Nevada.
Frankie, the head of the Corleone Family in NYC would then start agressions against the Rossato bros. By whacking Frank, and I do not feel they were trying to implicate Mike with Frank or his men, they would rid themselves (Roth and his allies) of a potential adversary.

Plus by clipping Pentagili, they would weaken Mikes power outside of his home base in Nevada.