Rebels broke into the Taftanaz base in north-western Idlib province but were pushed back by the army, rebel sources and state media said.
Reports said Aleppo airport was also under siege, and has been closed since Tuesday because of repeated attacks.
The attacks come a day after a UN study said 60,000 people had died in Syria.
A study commissioned by UN human rights commissioner Navi Pillay concluded that there had been 59,648 deaths between February 2011 and November 2012, and that figure would now have risen above 60,000.
She described the bloodshed as "truly shocking".
Syrian opposition groups had previously estimated 45,000 people killed.
The attack on Taftanaz began on Wednesday, with rebels breaking into the base and detonating a car bomb inside the grounds.
Unconfirmed reports said they had destroyed a fighter jet and a helicopter.
Further attacks followed on Thursday morning, but reports say the rebels have now been forced to withdraw. Several attempts to take the facility in recent months have failed.
State news agency Sana said government forces had "repelled the terrorists' attempt to attack the airport" and inflicted heavy losses.
More clashes were reported in suburbs of Damascus, with government troops trying to capture Daraya.
There was also fighting around the city and airport of Deir Ezzor.
Meanwhile the family of US freelance journalist James Foley have announced on Wednesday that he had gone missing near Taftanaz more than a month ago, shortly after entering Syria.
They had previously asked the media not to report his abduction.
Foley, 39, is described as an experienced war reporter. He was detained by Libyan government forces for six weeks in April 2011 while covering that conflict.

Outsourcing firm Capita was the leading gainer, up by 4% after a reassuring trading statement.
The company, which in February warned of lower margins, said it was on track to meet expectations for 2016 revenue growth. The statement was described as "unusually numbers light" by one broker.
The FTSE 100 was up 38.92 points at 6,153.73.
Shares in Easyjet, which reported a loss - largely thanks to adverse currency movements - fell 0.4% after its gain of 3.8% on Monday.
There was the usual volatility in mining stocks. On Monday the index was dragged down by these with Anglo American losing 13.8%. Morning Tuesday trade sees them recover 3.4%.
On the currency markets, the pound rose 0.21% against the dollar to $1.4438 but was flat against the euro to â‚¬1.2669.
Fierce battles are taking place at some northern Syrian airports, as rebels try to neutralise the government's overwhelming air advantage.
[NEXT_CONCEPT]
(Open): London's FTSE 100 started higher on Tuesday.