Ok let's get technical here.
LeBron committed to the Cavs on 7/11, but he didn't sign with the Cavs until 7/12.
If he called Love the night he committed, he was still a free agent, so can a free agent tamper?
Anyway, I bet saltlover chimes in soon with the exact answer to all of our tampering questions. Dude has the CBA memorized. Of course one of us could just google it and look it up ourselves, I would but for some reason when I try to go to the cbafaq.com site from work, I got the message that it's blocked "Reason: Not allowed to browse P0rnography category", go figure).
LOL. TP for making me log on.
LeBron could probably be fined for tampering with Love if the NBA wanted to do so. Love was under contract with the Wolves, and James was telling him he wanted to play with Love on a team other than the Wolves. It shouldn't matter whether or not LeBron was technically under contract with Cleveland at that point. LeBron was still considered an active NBA player and bound by the rules of the CBA -- I'm quite certain he could have been drug tested on July 8th, for example (not trying to sidetrack the discussion about LeBron and his suspected PED usage held by some fans).
The NBA has stayed away from fining players for tampering in general -- it's very difficult to prove, and the league knows players talk, and bond at events like the US National Team and All-Star games -- both of which help promote the NBA product. LeBron might get a warning since Love admitted something publicly, and the league was rather annoyed that the negotiations for the trade dragged out in public for about six weeks. They could even fine him a nominal sum to make an example, but I'd doubt they would. They much more care about enforcing the rule on teams and executives, since those are the people who actually have the authority to sign players and make trades. Also, in the grand scheme of creating good relations with players, fining them $5k-$25k for off-court communications seems like a bad thing to fight over. Much better to fight over the split of revenue.
Short of LeBron holding a press conference to demand the Cavs trade for Love, I wouldn't see the NBA acting on this. Again, maybe he'd get a warning. Doubtful, but maybe. He'd probably have to get multiple warnings before being fined though.