The pair, who play Walford's Sharon Rickman and Kat Moon respectively, spoke out after magazines claimed that they are unhappy to be working together again.
Dean returned to screens as Sharon on Monday following a six-year absence from the BBC soap. However, some reports this week have suggested that Wallace is 'snubbing' her colleague and is fearful over her own future with the programme.
An EastEnders spokesperson told Digital Spy today (August 15): "There is absolutely no truth in the reports that Jessie and Letitia do not get on or that the atmosphere at EastEnders can be 'cut with a knife'.
"Jessie has no fears that she is being 'phased out' of EastEnders, in fact she has huge storylines to come for the rest of the year and beyond and Kat remains a key part of the show.
"As we have always said, Letitia is not a replacement for Jessie - she is yet another great addition to our cast."
Jessie Wallace added: "Yet again, I seem to have a problem with Letitia Dean, which is funny considering we were hysterically laughing only a couple of days ago.
"I do wish people would stop trying to cause trouble between the two of us, it is not only untrue but incredibly boring. Maybe whoever prints these stories should write a book as this article is nothing but a work of fiction."
Meanwhile, Letitia Dean told Digital Spy: "I love being back at EastEnders and the atmosphere is better than ever.
"Any suggestions that Jessie and I don't get on are completely untrue, in fact Jessie was the first person to call and congratulate me when it was announced that I was returning. The only downside about returning is reading claims in certain magazines that are completely untrue."
Dean announced her EastEnders return in February.