Interference

You may be looking for the two-part novel of the same name.

Interference in the affairs of other beings was one of the gravest offences a Time Lord could commit. The Sixth Doctor's trial, as prosecuted by the Valeyard, had interference as its main charge. (TV: The Mysterious Planet)

In 2526, a Cyber-Lieutenant believed that the Time Lords were forbidden to interfere, though his Cyber-Leader observed that the Doctor did "nothing else but interfere". (TV: Earthshock)