The law firm acting on behalf of Paddy Jackson says it intends to sue Senator Aodhain O'Riordain for defamation.
The Ulster and Ireland player was acquitted of rape and sexual assault at Belfast Crown Court earlier this week.
Soon after the verdict was handed down Senator O'Riordain tweeted his reaction but the post was later deleted.
KRW Law says it will not hesitate to repeat similar legal action against anyone who deliberately or otherwise attacks its client.
