No, Jesus was not a vegetarian. He partook of the Passover Meal which was lamb.
- Exodus 12:3, 6-7, 11, “Speak to all the congregation of Israel, saying, ‘On the tenth of this month they are each one to take a lamb for themselves, according to their fathers’ households, a lamb for each household” . . . " 6‘ And you shall keep it until the fourteenth day of the same month, then the whole assembly of the congregation of Israel is to kill it at twilight. 7 ‘Moreover, they shall take some of the blood and put it on the two doorposts and on the lintel of the houses in which they eat it . . . 11 ‘Now you shall eat it in this manner: with your loins girded, your sandals on your feet, and your staff in your hand; and you shall eat it in haste--it is the LORD’S Passover.”
- Mark 14:13-14, And He sent two of His disciples, and said to them, “Go into the city, and a man will meet you carrying a pitcher of water; follow him; 14 and wherever he enters, say to the owner of the house, ‘The Teacher says, “Where is My guest room in which I may eat the Passover with My disciples?'"
It is not wrong to be a vegetarian. Each person is free to make that choice for himself, (Rom. 14:1-12).