The 35-year-old, who previously played for the Santiago Bernabeu outfit, has shown his sense of humour in his verdict over whether the defender used his hand to keep the ball out
Betis, who had already had an appeal for a penalty turned down after the ball hit Xabi Alonso, believed they had solid grounds for a spot-kick when Ramos appeared to repeat the midfielder's actions during stoppage time.
However Guti, who is currently unattached after leaving Besiktas in November, joked about the incident on Twitter.
"Great match from Real Madrid at Betis and a great stop by Sergio Ramos. In the last second my good friend proved himself as a great defender and goalkeeper," Guti tweeted.
Madrid are now 13 points clear of Barcelona at the top of La Liga, but Pep Guardiola's men can close the gap to 10 with a win against Racing Santander on Sunday.