Mata made no mention of claims he and team-mate John Obi Mikel were the victims of comments made toward them by Clattenburg, which are understood to have been interpreted as racist.
Clattenburg himself last night promised to co-operate with any investigation into the events that took place in yesterday's Barclays Premier League match at Stamford Bridge, which United won 3-2.
The official also stood by his controversial decision to show Fernando Torres a second yellow card for diving, according to former referee Dermot Gallagher, who claimed to have spoken to the 37-year-old last night.
Replays clearly showed Torres had been fouled by Jonny Evans and the sending-off reduced Chelsea to nine men, allowing United to score a winner which itself should have been disallowed for offside.
Mata wrote on http://blogs.grada360.com/juanmata: "This time I'm writing to you from home, just arrived from Stamford Bridge, and obviously disappointed after our defeat.
"It was a very important match for us, first vs second, and we were eager to win in order to open a gap at the top of the table. Yet we couldn't make it.
"The match started bad for us, conceding two goals in the early minutes (the first one very unlucky), but there was plenty of time to fight back. And we did it.
"Little by little, with the support of the crowd, we put more and more pressure on United and we managed to tie the game thanks to a very intense start in the second half.
"But soon afterwards, when the team's belief was higher, we had to play with nine men after Torres being unfairly sent off.
"Yet I prefer to be positive, we were very competitive against a great rival and we fought back with 0-2. Also we keep at the top of the table. It's still too early, but it's important to be up there.
"But football keeps going, there is no time to look back and this coming Wednesday we are again facing United, again at Stamford Bridge.
"The Capital One [Cup] this time. I hope we can win and forget today's defeat..."