Garcia was observed undergoing shoulder treatment on the course after struggling to play out of the thick rough, and finished with a 76.
But Warren had little sympathy, saying: "If it's dangerous you can chip it five yards back on to the fairway, if you like."
Garcia's struggles left the world No.10, who is now in doubt for the second round, lying nine shots shy of the leading trio of England's Matthew Baldwin, Frenchman Romain Wattel and Spain's Rafa Cabrera-Bello.
Warren and his fellow Scot Craig Lee, along with the European Ryder Cup captain Paul McGinley, are next best on four under par in the $2.7m event in the UAE capital.
Garcia was heading for further treatment at the close of his round and expressing uncertainty on his continuation in the event. "I hurt my left shoulder in the Pro-Am yesterday and the rough this week is not helping it very much," the Spaniard said.
"It's very, very thick and what we see at a US Open but the worst thing about it is they have cut it from green back to the tee, and by doing that the ball nestles down quite a bit. You just have to hit it so hard into the ground to get it out and when you're not 100% it doesn't help at all.
"I would say that it's dangerous and hopefully nobody else will get injured because it could have to several guys this week. There wasn't a specific shot in the Pro Am when I felt I injured my shoulder but just the more I continued to play yesterday.
"Maybe I injured a bit working throughout the Christmas break and it just kind of built up somewhat."
While Garcia was critical with the National Course set-up, double major champion Rory McIlroy had no such problems during his round of a two-under-par 70. McIlroy's effort is seven shots fewer than a year ago when he competed for a first time after signing a $225m deal to switch to Nike.
"It's not dangerous and besides we face worst at the US Open; if you get a bad lie, just chop it out," said the Northern Irishman.
Warren's round is his lowest starting effort in nine straight years teeing-up in Abu Dhabi. It is also his equal-lowest overall in 21 rounds of the Peter Harradine-designed National Course and only the third occasion he has broken 70.
"It was just a matter of trying to get into playing mode," said Warren. "I got into Dubai a little bit later, and I haven't had to undertake as much technical work so I've been ready to play and that proved right today."
Lee burst up the board on the back of four birdies in succession from his 14th hole and in a score four shots fewer than his 72 on debut in Abu Dhabi a year ago.
"I'm starting to believe in myself a wee bit more," he said. "Before, you thought you maybe had a game but until you actually prove it . . . "