You can ask him if he would like to be a good boy and stay off the table, or if he would like to come sit with you. Or, more age appropriate, tell him No Owies and make him come sit with you for a few minutes. Or better yet, sit on the couch and make him sit on the floor in front of you. It only took about 3 times of that for my daycare little one to quit trying to find a way under the stairway safety gate.
Bottom line, you just can't call it a time out until they're 2. But he's old enough for rules to be enforced.