Is it possible to be a Cardiologist if you have Tremors in your hands

Yes. but there would still be challenges.
Some cardiologists r non-interventional. That means they do not perform cardiac catheterizations or other invasive procedures requiring steady hands & dexterity.

Cardiologists r internists. Most internal medicine is cerebral. They analyse, diagnose & treat cardiovascular conditions through non-invasive means. Cardiologists will refer to a cardiothoracic surgeon, interventional cardiologist if medical therapy fails.

Now the down side: every cardiology fellow must perform a certain number of interventional procedures during their training in order to complete the fellowship. It does not matter if they intend to do interventions later in their career.

If u have debilitating tremors it would be a challenge to become a cardiologist but not impossible.

Consider other medical specialties such as nephrology which require little or no manual dexterity.

EDIT:
If u r passionate about the study of the cardiovascular system why not become a medical scientist. There r a seemingly endless variety of investigations & research topics related to cardiac physiology, electrophysiology, & pharmacology. I even know a scientist who specializes in cardiovascular histopathology.
In sum, u do not have to go to medical school to study the heart.
Look into PhD programs at the major universities in ur area.