Roth had to know, for two reasons:
First, he needed to be aware that Michael was coming so he'd be ready for their meeting--and to dispatch Johnny Ola to greet him and direct him to Roth's home.
Second, as I posted elsewhere: Immediately after the shooting, Michael was certain, or almost certain, that Roth had ordered it. Though he was the target, Roth showed he had no compunctions about mowing down Kay or anyone else who got in the way. Since Roth had help, there was a traitor at the compound--and the traitor could organize another, even more ruthless, attempt on Michael that could endanger his family. So, he needed to remove the target (himself) and at the same time buy time from Roth until he could identify the traitor. As long as Roth thought he could lure Michael to Havana and get the $2 million from him, Michael and his family were (temporarily) safe. So, I'm guessing, he or Tom contacted Roth before he left Tahoe to let him know he was coming. The long trip would extend the "safe" period.

Another nice little charade that Roth and Michael played on each other:
--Although Michael knew Roth was behind the Tahoe shooting, and figured he was safe as long as Roth thought he'd get the $2 million, Michael drove the car and the bodyguard sat in the back, looking out the window, as if they suspected an ambush from "the perps." Nice signal from Michael that he didn't suspect Roth, and thought he might be in danger from foes unknown.
--Although Roth knew he was behind the Tahoe shooting, he had Johnny Ola take an apparently circuitous route to his home, and run inside to make sure "things were ok," so Michael would think he (Roth) was in the same danger simply by hosting Michael.
Clever fellows.