Does Jesus call for pacifism in this verse?
1. Jesus called for his disciples to carry weapons in Luke 22:36-38. Peter is carrying a weapon in Matthew 26 and Jesus does not rebuke Peter for having it. Nor does Jesus say to get rid of it, only to put it back in its place. Jesus must be ok with his disciples carrying swords, swords used for self-defense. Therefore Jesus could not have been saying that it is wrong to defend oneself, or that we should all be pacifists.
2. What Jesus was saying is that he did not want Peter to stop the authorities who were arresting him and who would inevitably take him to his death, which he knew must happen. If Peter violently resisted the arrest of Jesus, likely causing a scuffle, a civil uprising could occur perhaps causing the death of Peter and others. Certainly this was not the best time for that.
3. When Jesus said “all who take the sword will perish by the sword,” I believe he meant that those who use the sword (weapons or fighting in general) to advance the Kingdom of God will not succeed. If Peter and the other disciples were to use their weapons to advance what they thought at that time was the Kingdom of God, they likely would have died. Nor should we spread the gospel today through violence. However, self-defense is good and wise.