It depends.
You have to realize that even if the charge were accurate that “the Jews” killed Jesus, we’re dealing with a very small subset of the Jews who were living at the time.
The majority of Jews living during the Second Temple Era (when Jesus lived) lived in the diaspora. They never saw Jesus or heard of him until after his death. Certainly, they weren’t responsible for his death.
Even among those who lived in Israel at the time, only a subset would have been present in Jerusalem, even during the pilgrimage festival of Passover. Surely those who were not in Jerusalem cannot be blamed for his death.
And even among those who were in Jerusalem, there was probably only a percentage that were present when Jesus’s death sentence was proclaimed and/or carried out. People who were at home taking care of their families, preparing for the holidays, or attending to other tasks and were nowhere near the events that occurred cannot be blamed either.
So, even if some Jews were guilty of causing Jesus’s death, that’s it — *some* Jews were guilty. To paint all Jews with a broad brush and proclaim them all as guilty is antisemetic. It’s literally akin to blaming all Christians (or any other group) for the misdeeds of a few.
And, furthermore, to blame the Jews throughout history who were born after the fact, and those who are alive today, is antisemitic. To ascribe blame and responsibility to someone for something that happened two millennia before they were born is irrational hatred, pure and simple.
So, is it antisemitic to say that there were some Jews who might have been involved in the events leading to Jesus’s death? No, it’s not (provided you’re not using it as an attempt to cast blame or aspersion on Jews today).
Is it antisemitic to say “the Jews” (as a whole or as a group) killed Jesus? Yes, it is.
Is it antisemitic to say that Jews today bear any guilt for his death? Absolutely, it is.