Can you block a punt in soccer?

Answer 1

A block is the act of legally stopping a defender from getting to the player in possession of the ball.
Therefore if there is not a player in possession of the ball no one can be technically blocked.

Answer 2

Yes

The above answer is wrong. A player may not change his position on the field to block a goalie's punt. It is officially delaying the restart of play and should be "rewarded" with a yellow card and a free kick for the defending team. The key is where the player was when the ball was collected by the keeper and where the player is when the ball is punted.

The above implies that a player may run across the field and dive into the play, like would be done in American football. That should result in a yellow card caution and free kick.