True ligatures, in the sense of a character made up of two enjoined letters, like œ or ﬂ, don’t really exist in Hebrew—with the possible exception of the double yod (ײַ), which was common in Yiddish, but little used in Hebrew (most people aren’t even aware that has its own keystroke).
If you mean instances of joined-up letters in modern Hebrew cursive (as I suspect you do), those are mostly precluded by the very nature of that cursive.
The Roman cursive and the Hebrew one occupy opposite halves of the “chirodynamic ellipse” (see illustration)—an unconscious template that a (righthanded) person uses when writing. Roman cursive letters tend to be based on the lower half of that ellipse, which promotes the writing of “u-like” characters. Hebrew cursive letters, however, tend to occupy the upper half of the same ellipse, resulting in resh-like characters:
The result is that Roman cursive lends itself naturally to joined up characters, whereas Hebrew ones militate against joining—i.e., characters tend to be formed clockwise, from 10 to 4, finishing at the baseline, which means that you can only join up with the next letter (to the left, of course), but crossing over the letter you’ve just written.
For this reason, Hebrew cursive characters tend to remain resolutely separate from one another. You can see this clearly when you compare the handwriting of someone who is equally at home in both languages (in this case, my late mother, as it happens) in English versus Hebrew:
Consequently, when people attempt to emulate Roman joined-up writing in Hebrew (typically, in creating a Hebrew version of a logo), it’s clearly forced and unnatural:
The only exceptions are combinations such as shin-lamed,or kaf-lamed, where the first letter ends near the base of the second:
another fairly common one is nun-heh—although that requires a more flagrant divergence from “proper” cursive writing:
Hope that answers your question.