No timescale for Murray's return after ankle injury
Murray said earlier this year he did not plan to "play much past this summer" after slipping down the world rankings due to fitness problems and a struggle to recapture his best form.
A two-time Wimbledon champion, Murray was preparing for a farewell appearance at the All England Club and hopes to take part in one more Olympic Games in Paris in July.
However, with just over three months until Wimbledon, Murray faces a race against time to be fit.
The Scot said he had suffered a full rupture of his anterior talofibular ligament and near full-thickness rupture of his calcaneofibular ligament in a third round defeat in Miami to Tomas Machac on Sunday.
"Following consultation with his team and medical experts, Andy Murray has taken the decision to miss the Rolex Monte Carlo Masters and BMW Open Munich," said a statement from Murray's management team on Friday.
"At this stage, it is still not clear how long Andy will be out of action, and he is continuing to review options with his medical team.
"Obviously this is very disappointing news for Andy and he has reiterated his desire to get back on court as soon as possible."
The two-time Olympic champion also has little time to qualify for the Paris Games.
Direct entry into the Olympic men's singles will be given to the top 56 players in the ATP rankings on June 10 with Murray currently 62 in the world.